Fix argument retrieval in native functions

Add parents to the VM; Improve the disassembler
Clean up
2024-11-07 03:05:32 -05:00 · 2024-11-07 02:10:02 -05:00 · 2024-11-07 00:49:36 -05:00 · 2024-11-06 19:18:38 -05:00 · 2024-11-06 18:39:09 -05:00 · 2024-11-06 17:59:16 -05:00
48 changed files with 8512 additions and 10842 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -4,9 +4,9 @@ version = 3

 [[package]]
 name = "aho-corasick"
-version = "1.1.2"
+version = "1.1.3"
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+checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
 dependencies = [
 "memchr",
 ]
@ -23,52 +23,65 @@ dependencies = [

 [[package]]
 name = "anstream"
-version = "0.6.13"
+version = "0.6.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d96bd03f33fe50a863e394ee9718a706f988b9079b20c3784fb726e7678b62fb"
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 dependencies = [
 "anstyle",
 "anstyle-parse",
 "anstyle-query",
 "anstyle-wincon",
 "colorchoice",
+ "is_terminal_polyfill",
 "utf8parse",
 ]

 [[package]]
 name = "anstyle"
-version = "1.0.8"
+version = "1.0.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1bec1de6f59aedf83baf9ff929c98f2ad654b97c9510f4e70cf6f661d49fd5b1"
+checksum = "55cc3b69f167a1ef2e161439aa98aed94e6028e5f9a59be9a6ffb47aef1651f9"

 [[package]]
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+checksum = "3b2d16507662817a6a20a9ea92df6652ee4f94f914589377d69f3b21bc5798a9"
 dependencies = [
 "utf8parse",
 ]

 [[package]]
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-version = "1.0.2"
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+checksum = "79947af37f4177cfead1110013d678905c37501914fba0efea834c3fe9a8d60c"
 dependencies = [
- "windows-sys",
+ "windows-sys 0.59.0",
 ]

 [[package]]
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+checksum = "2109dbce0e72be3ec00bed26e6a7479ca384ad226efdd66db8fa2e3a38c83125"
 dependencies = [
 "anstyle",
- "windows-sys",
+ "windows-sys 0.59.0",
 ]

+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "79296716171880943b8470b5f8d03aa55eb2e645a4874bdbb28adb49162e012c"
+
+[[package]]
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+checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
+
 [[package]]
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@ -77,9 +90,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"

 [[package]]
 name = "clap"
-version = "4.5.14"
+version = "4.5.20"
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-checksum = "c937d4061031a6d0c8da4b9a4f98a172fc2976dfb1c19213a9cf7d0d3c837e36"
+checksum = "b97f376d85a664d5837dbae44bf546e6477a679ff6610010f17276f686d867e8"
 dependencies = [
 "clap_builder",
 "clap_derive",
@ -87,9 +100,9 @@ dependencies = [

 [[package]]
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-version = "4.5.14"
+version = "4.5.20"
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-checksum = "85379ba512b21a328adf887e85f7742d12e96eb31f3ef077df4ffc26b506ffed"
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 dependencies = [
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 "anstyle",
@ -99,9 +112,9 @@ dependencies = [

 [[package]]
 name = "clap_derive"
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+version = "4.5.18"
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-checksum = "501d359d5f3dcaf6ecdeee48833ae73ec6e42723a1e52419c79abf9507eec0a0"
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@ -117,44 +130,30 @@ checksum = "1462739cb27611015575c0c11df5df7601141071f07518d56fcc1be504cbec97"

 [[package]]
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 [[package]]
-name = "crossbeam-deque"
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+name = "colored"
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-checksum = "613f8cc01fe9cf1a3eb3d7f488fd2fa8388403e97039e2f73692932e291a770d"
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 dependencies = [
- "crossbeam-epoch",
- "crossbeam-utils",
+ "lazy_static",
+ "windows-sys 0.48.0",
 ]

-[[package]]
-name = "crossbeam-epoch"
-version = "0.9.18"
-source = "registry+https://github.com/rust-lang/crates.io-index"
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-dependencies = [
- "crossbeam-utils",
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-
-[[package]]
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-
 [[package]]
 name = "dust-lang"
 version = "0.5.0"
 dependencies = [
 "annotate-snippets",
+ "colored",
 "env_logger",
+ "getrandom",
 "log",
 "rand",
- "rayon",
 "serde",
 "serde_json",
 ]
@ -164,21 +163,17 @@ name = "dust-shell"
 version = "0.1.0"
 dependencies = [
 "clap",
+ "colored",
 "dust-lang",
 "env_logger",
+ "log",
 ]

-[[package]]
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-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "11157ac094ffbdde99aa67b23417ebdd801842852b500e395a45a9c0aac03e4a"
-
 [[package]]
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-checksum = "a009aa4810eb158359dda09d0c87378e4bbb89b5a801f016885a4707ba24f7ea"
+checksum = "4f2c92ceda6ceec50f43169f9ee8424fe2db276791afde7b2cd8bc084cb376ab"
 dependencies = [
 "log",
 "regex",
@ -199,13 +194,15 @@ dependencies = [

 [[package]]
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+version = "0.2.15"
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+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
 dependencies = [
 "cfg-if",
+ "js-sys",
 "libc",
 "wasi",
+ "wasm-bindgen",
 ]

 [[package]]
@ -221,16 +218,37 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
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 [[package]]
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+dependencies = [
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+]
+
+[[package]]
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@ -240,30 +258,39 @@ checksum = "a7a70ba024b9dc04c27ea2f0c0548feb474ec5c54bba33a7f72f873a39d07b24"

 [[package]]
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+dependencies = [
+ "zerocopy",
+]

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@ -298,31 +325,11 @@ dependencies = [
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 ]

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- "crossbeam-utils",
-]
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 [[package]]
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 "memchr",
@ -332,9 +339,9 @@ dependencies = [

 [[package]]
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@ -343,30 +350,30 @@ dependencies = [

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@ -375,11 +382,12 @@ dependencies = [

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+ "memchr",
 "ryu",
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@ -392,9 +400,9 @@ checksum = "7da8b5736845d9f2fcb837ea5d9e2628564b3b043a70948a3f0b778838c5fb4f"

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@ -403,21 +411,21 @@ dependencies = [

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 dependencies = [
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+ "cfg-if",
+ "once_cell",
+ "wasm-bindgen-macro",
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+checksum = "1b9b4fd18abc82b8136838da5d50bae7bdea537c574d8dc1a34ed098d6c166f0"
+dependencies = [
+ "byteorder",
+ "zerocopy-derive",
+]
+
+[[package]]
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+]
--- a/README.md
+++ b/README.md
@ -1,109 +1,50 @@
 # Dust

-High-level programming language with effortless concurrency, automatic memory management and type
-safety.
+Dust is a high-level interpreted programming language with static types that focuses on ease of use,
+performance and correctness.

-Dust is a work in progress. Because it aims to deliver a high level of safety, extensive testing
-is required. The language is still in the design phase, and the syntax is subject to change.
+## Implementation

-## Usage
+Dust is implemented in Rust and is divided into several parts, primarily the lexer, compiler, and
+virtual machine. All of Dust's components are designed with performance in mind and the codebase
+uses as few dependencies as possible.

-The Dust command line tool can be used to run Dust programs. It is not yet available outside of
-this repository.
+### Lexer

-```sh
-cargo run --package dust-shell -- examples/hello_world.ds
-```
+The lexer emits tokens from the source code. Dust makes extensive use of Rust's zero-copy
+capabilities to avoid unnecessary allocations when creating tokens. A token, depending on its type,
+may contain a reference to some data from the source code. The data is only copied in the case of an
+error, because it improves the usability of the codebase for errors to own their data when possible.
+In a successfully executed program, no part of the source code is copied unless it is a string
+literal or identifier.

-```sh
-cargo run --package dust-shell -- -c '"Hello my name is " + read_line() + "!"'
-```
+### Compiler

-Dust is easily embedded in another program. You can run a dust program of any size or complexity
-with a single function.
+The compiler creates a chunk, which contains all of the data needed by the virtual machine to run a
+Dust program. It does so by emitting bytecode instructions, constants and locals while parsing the
+tokens, which are generated one at a time by the lexer.

-```rust
-use dust_lang::{run, Value};
+#### Parsing

-fn main() {
-    let code = "
-        let x = 'Dust'
-        let y = ' is awesome!'
+Dust's compiler uses a custom Pratt parser, a kind of recursive descent parser, to translate a
+sequence of tokens into a chunk.

-        write_line(x + y)
+#### Optimizing

-        42
-    ";
+When generating instructions for a register-based virtual machine, there are opportunities to
+optimize the generated code, usually by consolidating register use or reusing registers within an
+expression. While it is best to output optimal code in the first place, it is not always possible.
+Dust's compiler has a simple peephole optimizer that can be used to modify isolated sections of the
+instruction list through a mutable reference.

-    let result = run(code);
+### Instructions

-    assert_eq!(result, Ok(Some(Value::integer(42))));
-}
-```
+### Virtual Machine

-## Concepts
+## Previous Implementations

-### Effortless Concurrency
+## Inspiration

-Dust makes concurrency as effortless as possible. Dust is organized into **statements**, and any
-sequence of statements can be run concurrently by simply adding the `async` keyword before the block
-of statements.
-
-```rust
-// Counts from 0 to 9, sleeping for an increasing amount of time between each.
-let count_slowly = fn (multiplier: int) {
-    i = 0
-
-    while i < 10 {
-        sleep(i * multiplier)
-        write_line(i.to_string())
-
-        i += 1
-    }
-}
-
-async {
-    count_slowly(200) // Finishes last
-    count_slowly(100) // Finishes second
-    count_slowly(50)  // Finishes first
-}
-```
-
-### Automatic Memory Management
-
-Dust uses a garbage collector to automatically manage memory.
-
-```rust
-let x = 0     // x is assigned but never used
-              // x is removed from memory
-
-let y = 41    // y is assigned
-let z = y + 1 // y is kept alive for this statement
-              // y is removed from memory
-
-write_line(z) // z is kept alive for this statement
-              // z is removed from memory
-```
-
-### Type Safety
-
-Dust is statically typed and null-free, but the type of a value can usually be inferred from its
-usage. Dust will refuse to run programs with type errors, but will usually not require type
-annotations.
-
-```rust
-// These two statements are identical to Dust
-let x = 1
-let x: int = 1
-
-// Numbers with decimals are floats
-let y = 10.0
-let y: float = 10.0
-
-// Strings are enclosed in double quotes and are guaranteed to be valid UTF-8
-let z = "Hello, world!"
-let z: str = "Hello, world!"
-```
-
-Aside from the ubiqutous `bool`, `int`, `float`, and `str` types, Dust also has lists, maps,
-ranges, structures, enums and functions.
+- [The Implementation of Lua 5.0](https://www.lua.org/doc/jucs05.pdf)
+- [A No-Frills Introduction to Lua 5.1 VM Instructions](https://www.mcours.net/cours/pdf/hasclic3/hasssclic818.pdf)
+- [Crafting Interpreters](https://craftinginterpreters.com/)
--- a/dust-lang/Cargo.toml
+++ b/dust-lang/Cargo.toml
@ -10,12 +10,14 @@ repository.workspace = true

 [dependencies]
 annotate-snippets = "0.11.4"
-env_logger = "0.11.3"
+colored = "2.1.0"
 log = "0.4.22"
 rand = "0.8.5"
-rayon = "1.9.0"
 serde = { version = "1.0.203", features = ["derive"] }
 serde_json = "1.0.117"
+getrandom = { version = "0.2", features = [
+    "js",
+] } # Indirect dependency, for wasm builds

 [dev-dependencies]
 env_logger = "0.11.5"
--- a/dust-lang/src/analyzer.rs
+++ b/dust-lang/src/analyzer.rs
--- a/dust-lang/src/ast/expression.rs
+++ b/dust-lang/src/ast/expression.rs
--- a/dust-lang/src/ast/mod.rs
+++ b/dust-lang/src/ast/mod.rs
@ -1,192 +0,0 @@
-//! In-memory representation of a Dust program.
-mod expression;
-mod statement;
-
-pub use expression::*;
-pub use statement::*;
-
-use std::{
-    collections::VecDeque,
-    fmt::{self, Debug, Display, Formatter},
-    num::TryFromIntError,
-};
-
-use serde::{Deserialize, Serialize};
-
-use crate::{core_library, Context, ContextError};
-
-pub type Span = (usize, usize);
-
-/// In-memory representation of a Dust program.
-#[derive(Clone, Serialize, Deserialize)]
-pub struct AbstractSyntaxTree {
-    pub statements: VecDeque<Statement>,
-
-    #[serde(skip)]
-    pub context: Context,
-}
-
-impl Debug for AbstractSyntaxTree {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.debug_struct("AbstractSyntaxTree")
-            .field("statements", &self.statements)
-            .finish()
-    }
-}
-
-impl Eq for AbstractSyntaxTree {}
-
-impl PartialEq for AbstractSyntaxTree {
-    fn eq(&self, other: &Self) -> bool {
-        self.statements == other.statements
-    }
-}
-
-impl PartialOrd for AbstractSyntaxTree {
-    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-}
-
-impl Ord for AbstractSyntaxTree {
-    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
-        self.statements.cmp(&other.statements)
-    }
-}
-
-impl AbstractSyntaxTree {
-    pub fn new() -> Self {
-        Self {
-            statements: VecDeque::new(),
-            context: Context::new(),
-        }
-    }
-
-    pub fn with_statements<T: Into<VecDeque<Statement>>>(statements: T) -> Self {
-        Self {
-            statements: statements.into(),
-            context: Context::new(),
-        }
-    }
-
-    pub fn with_core_library() -> Self {
-        Self {
-            statements: VecDeque::new(),
-            context: core_library().create_child(),
-        }
-    }
-}
-
-impl Default for AbstractSyntaxTree {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub struct Node<T> {
-    pub inner: T,
-    pub position: Span,
-}
-
-impl<T> Node<T> {
-    pub fn new(inner: T, position: Span) -> Self {
-        Self { inner, position }
-    }
-}
-
-impl<T: Display> Display for Node<T> {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "{}", self.inner)
-    }
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub enum AstError {
-    ContextError {
-        error: ContextError,
-        position: Span,
-    },
-    ExpectedFunctionOrConstructor {
-        position: Span,
-    },
-    ExpectedInteger {
-        position: Span,
-    },
-    ExpectedListType {
-        position: Span,
-    },
-    ExpectedNonEmptyEvaluation {
-        position: Span,
-    },
-    ExpectedNonEmptyList {
-        position: Span,
-    },
-    ExpectedRangeableType {
-        position: Span,
-    },
-    ExpectedStructFieldsType {
-        position: Span,
-    },
-    ExpectedTupleType {
-        position: Span,
-    },
-    FromIntError {
-        error: TryFromIntError,
-        position: Span,
-    },
-}
-
-impl AstError {
-    pub fn position(&self) -> Span {
-        match self {
-            AstError::ContextError { position, .. } => *position,
-            AstError::ExpectedFunctionOrConstructor { position } => *position,
-            AstError::ExpectedInteger { position } => *position,
-            AstError::ExpectedListType { position } => *position,
-            AstError::ExpectedNonEmptyEvaluation { position } => *position,
-            AstError::ExpectedNonEmptyList { position } => *position,
-            AstError::ExpectedRangeableType { position } => *position,
-            AstError::ExpectedStructFieldsType { position } => *position,
-            AstError::ExpectedTupleType { position } => *position,
-            AstError::FromIntError { position, .. } => *position,
-        }
-    }
-}
-
-impl Display for AstError {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self {
-            AstError::ContextError { error, position } => {
-                write!(f, "Context error at {:?}: {}", position, error)
-            }
-            AstError::ExpectedFunctionOrConstructor { position } => {
-                write!(f, "Expected a function or constructor at {:?}", position)
-            }
-            AstError::ExpectedInteger { position } => {
-                write!(f, "Expected an integer at {:?}", position)
-            }
-            AstError::ExpectedListType { position } => {
-                write!(f, "Expected a type at {:?}", position)
-            }
-            AstError::ExpectedTupleType { position } => {
-                write!(f, "Expected a tuple type at {:?}", position)
-            }
-            AstError::ExpectedNonEmptyEvaluation { position } => {
-                write!(f, "Expected a type at {:?}", position)
-            }
-            AstError::ExpectedNonEmptyList { position } => {
-                write!(f, "Expected a non-empty list at {:?}", position)
-            }
-            AstError::ExpectedRangeableType { position } => {
-                write!(f, "Expected a rangeable type at {:?}", position)
-            }
-            AstError::ExpectedStructFieldsType { position } => {
-                write!(f, "Expected a struct type with fields at {:?}", position)
-            }
-            AstError::FromIntError { error, position } => {
-                write!(f, "Integer conversion error at {:?}: {}", position, error)
-            }
-        }
-    }
-}
--- a/dust-lang/src/ast/statement.rs
+++ b/dust-lang/src/ast/statement.rs
@ -1,187 +0,0 @@
-use std::fmt::{self, Display, Formatter};
-
-use serde::{Deserialize, Serialize};
-
-use crate::{Context, Identifier, Type, TypeEvaluation};
-
-use super::{AstError, Expression, Node, Span};
-
-#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub enum Statement {
-    Expression(Expression),
-    ExpressionNullified(Node<Expression>),
-    Let(Node<LetStatement>),
-    StructDefinition(Node<StructDefinition>),
-}
-
-impl Statement {
-    pub fn struct_definition(struct_definition: StructDefinition, position: Span) -> Self {
-        Statement::StructDefinition(Node::new(struct_definition, position))
-    }
-
-    pub fn position(&self) -> Span {
-        match self {
-            Statement::Expression(expression) => expression.position(),
-            Statement::ExpressionNullified(expression_node) => expression_node.position,
-            Statement::Let(r#let) => r#let.position,
-            Statement::StructDefinition(definition) => definition.position,
-        }
-    }
-
-    pub fn type_evaluation(&self, context: &Context) -> Result<TypeEvaluation, AstError> {
-        match self {
-            Statement::Expression(expression) => expression.type_evaluation(context),
-            Statement::ExpressionNullified(expression_node) => {
-                let type_evaluation = expression_node.inner.type_evaluation(context)?;
-
-                if let TypeEvaluation::Break(_) = type_evaluation {
-                    Ok(type_evaluation)
-                } else {
-                    Ok(TypeEvaluation::Return(None))
-                }
-            }
-            Statement::Let(_) => Ok(TypeEvaluation::Return(None)),
-            Statement::StructDefinition(_) => Ok(TypeEvaluation::Return(None)),
-        }
-    }
-}
-
-impl Display for Statement {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self {
-            Statement::Expression(expression) => write!(f, "{}", expression),
-            Statement::ExpressionNullified(expression) => write!(f, "{};", expression),
-            Statement::Let(r#let) => write!(f, "{};", r#let),
-            Statement::StructDefinition(struct_definition) => match &struct_definition.inner {
-                StructDefinition::Unit { name } => write!(f, "struct {};", name),
-                StructDefinition::Tuple { name, items } => {
-                    write!(f, "struct {name} {{ ")?;
-
-                    for (index, item) in items.iter().enumerate() {
-                        write!(f, "{}: {}", item, index)?;
-
-                        if index < items.len() - 1 {
-                            write!(f, ", ")?;
-                        }
-                    }
-
-                    write!(f, " }}")
-                }
-                StructDefinition::Fields { name, fields } => {
-                    write!(f, "struct {name} {{ ")?;
-
-                    for (index, (field, r#type)) in fields.iter().enumerate() {
-                        write!(f, "{}: {}", field, r#type)?;
-
-                        if index < fields.len() - 1 {
-                            write!(f, ", ")?;
-                        }
-                    }
-
-                    write!(f, " }}")
-                }
-            },
-        }
-    }
-}
-
-#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub enum LetStatement {
-    Let {
-        identifier: Node<Identifier>,
-        value: Expression,
-    },
-    LetMut {
-        identifier: Node<Identifier>,
-        value: Expression,
-    },
-    LetType {
-        identifier: Node<Identifier>,
-        r#type: Node<Type>,
-        value: Expression,
-    },
-    LetMutType {
-        identifier: Node<Identifier>,
-        r#type: Node<Type>,
-        value: Expression,
-    },
-}
-
-impl Display for LetStatement {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self {
-            LetStatement::Let { identifier, value } => {
-                write!(f, "let {identifier} = {value}")
-            }
-            LetStatement::LetMut { identifier, value } => {
-                write!(f, "let mut {identifier} = {value}")
-            }
-            LetStatement::LetType {
-                identifier,
-                r#type,
-                value,
-            } => {
-                write!(f, "let {identifier}: {type} = {value}")
-            }
-            LetStatement::LetMutType {
-                identifier,
-                r#type,
-                value,
-            } => {
-                write!(f, "let mut {identifier}: {type} = {value}")
-            }
-        }
-    }
-}
-
-#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub enum StructDefinition {
-    Unit {
-        name: Node<Identifier>,
-    },
-    Tuple {
-        name: Node<Identifier>,
-        items: Vec<Node<Type>>,
-    },
-    Fields {
-        name: Node<Identifier>,
-        fields: Vec<(Node<Identifier>, Node<Type>)>,
-    },
-}
-
-impl Display for StructDefinition {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self {
-            StructDefinition::Unit { name } => write!(f, "struct {name}"),
-            StructDefinition::Tuple {
-                name,
-                items: fields,
-            } => {
-                write!(f, "struct {name} {{")?;
-
-                for (i, field) in fields.iter().enumerate() {
-                    if i > 0 {
-                        write!(f, ", ")?;
-                    }
-
-                    write!(f, "{field}")?;
-                }
-
-                write!(f, "}}")
-            }
-            StructDefinition::Fields { name, fields } => {
-                write!(f, "struct {name} {{")?;
-
-                for (i, (field_name, field_type)) in fields.iter().enumerate() {
-                    if i > 0 {
-                        write!(f, ", ")?;
-                    }
-
-                    write!(f, "{field_name}: {field_type}")?;
-                }
-
-                write!(f, "}}")
-            }
-        }
-    }
-}
--- a/dust-lang/src/built_in_function.rs
+++ b/dust-lang/src/built_in_function.rs
@ -1,208 +0,0 @@
-//! Integrated functions that can be called from Dust code.
-use std::{
-    error::Error,
-    fmt::{self, Display, Formatter},
-    io::{self, stdin, stdout, Write},
-};
-
-use serde::{Deserialize, Serialize};
-
-use crate::{FunctionType, Identifier, Type, Value, ValueData, ValueError};
-
-/// Integrated function that can be called from Dust code.
-#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
-pub enum BuiltInFunction {
-    // String tools
-    ToString,
-
-    // Integer and float tools
-    IsEven,
-    IsOdd,
-
-    // I/O
-    ReadLine,
-    WriteLine,
-}
-
-impl BuiltInFunction {
-    pub fn name(&self) -> &'static str {
-        match self {
-            BuiltInFunction::IsEven => "is_even",
-            BuiltInFunction::IsOdd => "is_odd",
-            BuiltInFunction::ReadLine => "read_line",
-            BuiltInFunction::ToString { .. } => "to_string",
-            BuiltInFunction::WriteLine => "write_line",
-        }
-    }
-
-    pub fn type_parameters(&self) -> Option<Vec<Identifier>> {
-        match self {
-            BuiltInFunction::ToString { .. } => None,
-            BuiltInFunction::IsEven => None,
-            BuiltInFunction::IsOdd => None,
-            BuiltInFunction::ReadLine => None,
-            BuiltInFunction::WriteLine => None,
-        }
-    }
-
-    pub fn value_parameters(&self) -> Option<Vec<(Identifier, Type)>> {
-        match self {
-            BuiltInFunction::ToString { .. } => Some(vec![("value".into(), Type::Any)]),
-            BuiltInFunction::IsEven => Some(vec![("value".into(), Type::Number)]),
-            BuiltInFunction::IsOdd => Some(vec![("value".into(), Type::Number)]),
-            BuiltInFunction::ReadLine => None,
-            BuiltInFunction::WriteLine => Some(vec![("value".into(), Type::Any)]),
-        }
-    }
-
-    pub fn return_type(&self) -> Option<Type> {
-        match self {
-            BuiltInFunction::ToString { .. } => Some(Type::String { length: None }),
-            BuiltInFunction::IsEven => Some(Type::Boolean),
-            BuiltInFunction::IsOdd => Some(Type::Boolean),
-            BuiltInFunction::ReadLine => Some(Type::String { length: None }),
-            BuiltInFunction::WriteLine => None,
-        }
-    }
-
-    pub fn r#type(&self) -> Type {
-        Type::Function(FunctionType {
-            name: Identifier::new(self.name()),
-            type_parameters: self.type_parameters(),
-            value_parameters: self.value_parameters(),
-            return_type: self.return_type().map(Box::new),
-        })
-    }
-
-    pub fn call(
-        &self,
-        _type_arguments: Option<Vec<Type>>,
-        value_arguments: Option<Vec<Value>>,
-    ) -> Result<Option<Value>, BuiltInFunctionError> {
-        match (self.value_parameters(), &value_arguments) {
-            (Some(value_parameters), Some(value_arguments)) => {
-                if value_parameters.len() != value_arguments.len() {
-                    return Err(BuiltInFunctionError::WrongNumberOfValueArguments);
-                }
-            }
-            (Some(_), None) | (None, Some(_)) => {
-                return Err(BuiltInFunctionError::WrongNumberOfValueArguments);
-            }
-            (None, None) => {}
-        }
-
-        match self {
-            BuiltInFunction::ToString => {
-                Ok(Some(Value::string(value_arguments.unwrap()[0].to_string())))
-            }
-            BuiltInFunction::IsEven => {
-                let is_even = value_arguments.unwrap()[0].is_even()?;
-
-                Ok(Some(is_even))
-            }
-            BuiltInFunction::IsOdd => {
-                let is_odd = value_arguments.unwrap()[0].is_odd()?;
-
-                Ok(Some(is_odd))
-            }
-            BuiltInFunction::ReadLine => {
-                let mut input = String::new();
-
-                stdin().read_line(&mut input)?;
-
-                Ok(Some(Value::string(input.trim_end_matches('\n'))))
-            }
-            BuiltInFunction::WriteLine => {
-                let first_argument = &value_arguments.unwrap()[0];
-
-                match first_argument {
-                    Value::Raw(ValueData::String(string)) => {
-                        let mut stdout = stdout();
-
-                        stdout.write_all(string.as_bytes())?;
-                        stdout.write_all(b"\n")?;
-
-                        Ok(None)
-                    }
-
-                    Value::Reference(reference) => match reference.as_ref() {
-                        ValueData::String(string) => {
-                            let mut stdout = stdout();
-
-                            stdout.write_all(string.as_bytes())?;
-                            stdout.write_all(b"\n")?;
-
-                            Ok(None)
-                        }
-                        _ => Err(BuiltInFunctionError::ExpectedString),
-                    },
-                    Value::Mutable(locked) => {
-                        let value_data = &*locked.read().unwrap();
-                        let string = match value_data {
-                            ValueData::String(string) => string,
-                            _ => return Err(BuiltInFunctionError::ExpectedString),
-                        };
-
-                        let mut stdout = stdout();
-
-                        stdout.write_all(string.as_bytes())?;
-                        stdout.write_all(b"\n")?;
-
-                        Ok(None)
-                    }
-
-                    _ => Err(BuiltInFunctionError::ExpectedString),
-                }
-            }
-        }
-    }
-}
-
-impl Display for BuiltInFunction {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "{}", self.name())
-    }
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub enum BuiltInFunctionError {
-    Io(io::ErrorKind),
-    ValueError(ValueError),
-
-    ExpectedString,
-    ExpectedList,
-    ExpectedInteger,
-
-    WrongNumberOfValueArguments,
-}
-
-impl From<ValueError> for BuiltInFunctionError {
-    fn from(v: ValueError) -> Self {
-        Self::ValueError(v)
-    }
-}
-
-impl From<io::Error> for BuiltInFunctionError {
-    fn from(error: io::Error) -> Self {
-        Self::Io(error.kind())
-    }
-}
-
-impl Error for BuiltInFunctionError {}
-
-impl Display for BuiltInFunctionError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
-        match self {
-            BuiltInFunctionError::Io(error_kind) => write!(f, "I/O error: {}", error_kind),
-            BuiltInFunctionError::ValueError(value_error) => {
-                write!(f, "Value error: {}", value_error)
-            }
-            BuiltInFunctionError::ExpectedInteger => write!(f, "Expected an integer"),
-            BuiltInFunctionError::ExpectedString => write!(f, "Expected a string"),
-            BuiltInFunctionError::ExpectedList => write!(f, "Expected a list"),
-            BuiltInFunctionError::WrongNumberOfValueArguments => {
-                write!(f, "Wrong number of value arguments")
-            }
-        }
-    }
-}
--- a/dust-lang/src/chunk.rs
+++ b/dust-lang/src/chunk.rs
@ -0,0 +1,402 @@
+//! In-memory representation of a Dust program or function.
+//!
+//! A chunk consists of a sequence of instructions and their positions, a list of constants, and a
+//! list of locals that can be executed by the Dust virtual machine. Chunks have a name when they
+//! belong to a named function.
+
+use std::{
+    cmp::Ordering,
+    fmt::{self, Debug, Display, Formatter},
+};
+
+use serde::{Deserialize, Serialize};
+
+use crate::{Disassembler, Instruction, Operation, Span, Type, Value};
+
+/// In-memory representation of a Dust program or function.
+///
+/// See the [module-level documentation](index.html) for more information.
+#[derive(Clone, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct Chunk {
+    name: Option<String>,
+    pub is_poisoned: bool,
+
+    instructions: Vec<(Instruction, Span)>,
+    constants: Vec<Value>,
+    locals: Vec<Local>,
+
+    current_scope: Scope,
+    block_index: u8,
+}
+
+impl Chunk {
+    pub fn new(name: Option<String>) -> Self {
+        Self {
+            name,
+            is_poisoned: false,
+            instructions: Vec::new(),
+            constants: Vec::new(),
+            locals: Vec::new(),
+            current_scope: Scope::default(),
+            block_index: 0,
+        }
+    }
+
+    pub fn with_data(
+        name: Option<String>,
+        instructions: Vec<(Instruction, Span)>,
+        constants: Vec<Value>,
+        locals: Vec<Local>,
+    ) -> Self {
+        Self {
+            name,
+            is_poisoned: false,
+            instructions,
+            constants,
+            locals,
+            current_scope: Scope::default(),
+            block_index: 0,
+        }
+    }
+
+    pub fn name(&self) -> Option<&String> {
+        self.name.as_ref()
+    }
+
+    pub fn set_name(&mut self, name: String) {
+        self.name = Some(name);
+    }
+
+    pub fn len(&self) -> usize {
+        self.instructions.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.instructions.is_empty()
+    }
+
+    pub fn constants(&self) -> &Vec<Value> {
+        &self.constants
+    }
+
+    pub fn constants_mut(&mut self) -> &mut Vec<Value> {
+        &mut self.constants
+    }
+
+    pub fn take_constants(self) -> Vec<Value> {
+        self.constants
+    }
+
+    pub fn instructions(&self) -> &Vec<(Instruction, Span)> {
+        &self.instructions
+    }
+
+    pub fn instructions_mut(&mut self) -> &mut Vec<(Instruction, Span)> {
+        &mut self.instructions
+    }
+
+    pub fn get_instruction(&self, index: usize) -> Result<&(Instruction, Span), ChunkError> {
+        self.instructions
+            .get(index)
+            .ok_or(ChunkError::InstructionIndexOutOfBounds { index })
+    }
+
+    pub fn locals(&self) -> &Vec<Local> {
+        &self.locals
+    }
+
+    pub fn locals_mut(&mut self) -> &mut Vec<Local> {
+        &mut self.locals
+    }
+
+    pub fn get_local(&self, index: u8) -> Result<&Local, ChunkError> {
+        self.locals
+            .get(index as usize)
+            .ok_or(ChunkError::LocalIndexOutOfBounds {
+                index: index as usize,
+            })
+    }
+
+    pub fn get_local_mut(&mut self, index: u8) -> Result<&mut Local, ChunkError> {
+        self.locals
+            .get_mut(index as usize)
+            .ok_or(ChunkError::LocalIndexOutOfBounds {
+                index: index as usize,
+            })
+    }
+
+    pub fn current_scope(&self) -> Scope {
+        self.current_scope
+    }
+
+    pub fn get_constant(&self, index: u8) -> Result<&Value, ChunkError> {
+        self.constants
+            .get(index as usize)
+            .ok_or(ChunkError::ConstantIndexOutOfBounds {
+                index: index as usize,
+            })
+    }
+
+    pub fn push_or_get_constant(&mut self, value: Value) -> u8 {
+        if let Some(index) = self
+            .constants
+            .iter()
+            .position(|constant| constant == &value)
+        {
+            return index as u8;
+        }
+
+        self.constants.push(value);
+
+        (self.constants.len() - 1) as u8
+    }
+
+    pub fn get_identifier(&self, local_index: u8) -> Option<String> {
+        self.locals.get(local_index as usize).and_then(|local| {
+            self.constants
+                .get(local.identifier_index as usize)
+                .map(|value| value.to_string())
+        })
+    }
+
+    pub fn begin_scope(&mut self) {
+        self.block_index += 1;
+        self.current_scope.block_index = self.block_index;
+        self.current_scope.depth += 1;
+    }
+
+    pub fn end_scope(&mut self) {
+        self.current_scope.depth -= 1;
+
+        if self.current_scope.depth == 0 {
+            self.current_scope.block_index = 0;
+        } else {
+            self.current_scope.block_index -= 1;
+        }
+    }
+
+    pub fn expect_not_poisoned(&self) -> Result<(), ChunkError> {
+        if self.is_poisoned {
+            Err(ChunkError::PoisonedChunk)
+        } else {
+            Ok(())
+        }
+    }
+
+    pub fn get_constant_type(&self, constant_index: u8) -> Option<Type> {
+        self.constants
+            .get(constant_index as usize)
+            .map(|value| value.r#type())
+    }
+
+    pub fn get_local_type(&self, local_index: u8) -> Option<Type> {
+        self.locals.get(local_index as usize)?.r#type.clone()
+    }
+
+    pub fn get_register_type(&self, register_index: u8) -> Option<Type> {
+        let local_type_option = self
+            .locals
+            .iter()
+            .find(|local| local.register_index == register_index)
+            .map(|local| local.r#type.clone());
+
+        if let Some(local_type) = local_type_option {
+            return local_type;
+        }
+
+        self.instructions
+            .iter()
+            .enumerate()
+            .find_map(|(index, (instruction, _))| {
+                if let Operation::LoadList = instruction.operation() {
+                    if instruction.a() == register_index {
+                        let mut length = (instruction.c() - instruction.b() + 1) as usize;
+                        let mut item_type = Type::Any;
+                        let distance_to_end = self.len() - index;
+
+                        for (instruction, _) in self
+                            .instructions()
+                            .iter()
+                            .rev()
+                            .skip(distance_to_end)
+                            .take(length)
+                        {
+                            if let Operation::Close = instruction.operation() {
+                                length -= (instruction.c() - instruction.b()) as usize;
+                            } else if let Type::Any = item_type {
+                                item_type = instruction.yielded_type(self).unwrap_or(Type::Any);
+                            }
+                        }
+
+                        return Some(Type::List {
+                            item_type: Box::new(item_type),
+                            length,
+                        });
+                    }
+                }
+
+                if instruction.yields_value() && instruction.a() == register_index {
+                    instruction.yielded_type(self)
+                } else {
+                    None
+                }
+            })
+    }
+
+    pub fn return_type(&self) -> Option<Type> {
+        let returns_value = self
+            .instructions()
+            .last()
+            .map(|(instruction, _)| {
+                debug_assert!(matches!(instruction.operation(), Operation::Return));
+
+                instruction.b_as_boolean()
+            })
+            .unwrap_or(false);
+
+        if returns_value {
+            self.instructions.iter().rev().find_map(|(instruction, _)| {
+                if instruction.yields_value() {
+                    instruction.yielded_type(self)
+                } else {
+                    None
+                }
+            })
+        } else {
+            None
+        }
+    }
+
+    pub fn disassembler(&self) -> Disassembler {
+        Disassembler::new(self)
+    }
+}
+
+impl Display for Chunk {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let disassembler = self.disassembler().styled(false);
+
+        write!(f, "{}", disassembler.disassemble())
+    }
+}
+
+impl Debug for Chunk {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let disassembly = self.disassembler().styled(false).disassemble();
+
+        if cfg!(debug_assertions) {
+            write!(f, "\n{}", disassembly)
+        } else {
+            write!(f, "{}", disassembly)
+        }
+    }
+}
+
+impl Eq for Chunk {}
+
+impl PartialEq for Chunk {
+    fn eq(&self, other: &Self) -> bool {
+        self.instructions == other.instructions
+            && self.constants == other.constants
+            && self.locals == other.locals
+    }
+}
+
+/// A scoped variable.
+#[derive(Debug, Clone, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct Local {
+    /// The index of the identifier in the constants table.
+    pub identifier_index: u8,
+
+    /// The expected type of the local's value.
+    pub r#type: Option<Type>,
+
+    /// Whether the local is mutable.
+    pub is_mutable: bool,
+
+    /// Scope where the variable was declared.
+    pub scope: Scope,
+
+    /// Expected location of a local's value.
+    pub register_index: u8,
+}
+
+impl Local {
+    /// Creates a new Local instance.
+    pub fn new(
+        identifier_index: u8,
+        r#type: Option<Type>,
+        mutable: bool,
+        scope: Scope,
+        register_index: u8,
+    ) -> Self {
+        Self {
+            identifier_index,
+            r#type,
+            is_mutable: mutable,
+            scope,
+            register_index,
+        }
+    }
+}
+
+/// Variable locality, as defined by its depth and block index.
+///
+/// The `block index` is a unique identifier for a block within a chunk. It is used to differentiate
+/// between blocks that are not nested together but have the same depth, i.e. sibling scopes. If the
+/// `block_index` is 0, then the scope is the root scope of the chunk. The `block_index` is always 0
+/// when the `depth` is 0. See [Chunk::begin_scope][] and [Chunk::end_scope][] to see how scopes are
+/// incremented and decremented.
+#[derive(Debug, Clone, Copy, Default, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
+pub struct Scope {
+    /// Level of block nesting.
+    pub depth: u8,
+    /// Index of the block in the chunk.
+    pub block_index: u8,
+}
+
+impl Scope {
+    pub fn new(depth: u8, block_index: u8) -> Self {
+        Self { depth, block_index }
+    }
+
+    pub fn contains(&self, other: &Self) -> bool {
+        match self.depth.cmp(&other.depth) {
+            Ordering::Less => false,
+            Ordering::Greater => self.block_index >= other.block_index,
+            Ordering::Equal => self.block_index == other.block_index,
+        }
+    }
+}
+
+impl Display for Scope {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "({}, {})", self.depth, self.block_index)
+    }
+}
+
+/// Errors that can occur when using a [`Chunk`].
+#[derive(Clone, Debug, PartialEq)]
+pub enum ChunkError {
+    ConstantIndexOutOfBounds { index: usize },
+    InstructionIndexOutOfBounds { index: usize },
+    LocalIndexOutOfBounds { index: usize },
+    PoisonedChunk,
+}
+
+impl Display for ChunkError {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        match self {
+            ChunkError::ConstantIndexOutOfBounds { index } => {
+                write!(f, "Constant index {} out of bounds", index)
+            }
+            ChunkError::InstructionIndexOutOfBounds { index } => {
+                write!(f, "Instruction index {} out of bounds", index)
+            }
+            ChunkError::LocalIndexOutOfBounds { index } => {
+                write!(f, "Local index {} out of bounds", index)
+            }
+            ChunkError::PoisonedChunk => write!(f, "Chunk is poisoned"),
+        }
+    }
+}
--- a/dust-lang/src/compiler.rs
+++ b/dust-lang/src/compiler.rs
--- a/dust-lang/src/constructor.rs
+++ b/dust-lang/src/constructor.rs
@ -1,107 +0,0 @@
-use std::{
-    collections::HashMap,
-    fmt::{self, Display, Formatter},
-};
-
-use serde::{Deserialize, Serialize};
-
-use crate::{Identifier, Struct, StructType, TypeConflict, Value};
-
-#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
-pub struct Constructor {
-    pub struct_type: StructType,
-}
-
-impl Constructor {
-    pub fn construct_unit(&self) -> Result<Value, ConstructError> {
-        if let StructType::Unit { name } = &self.struct_type {
-            Ok(Value::r#struct(Struct::Unit { name: name.clone() }))
-        } else {
-            Err(ConstructError::ExpectedUnit)
-        }
-    }
-
-    pub fn construct_tuple(&self, fields: Vec<Value>) -> Result<Value, ConstructError> {
-        if let StructType::Tuple {
-            name: expected_name,
-            fields: expected_fields,
-        } = &self.struct_type
-        {
-            if fields.len() != expected_fields.len() {
-                return Err(ConstructError::FieldCountMismatch);
-            }
-
-            for (i, value) in fields.iter().enumerate() {
-                let expected_type = expected_fields.get(i).unwrap();
-                let actual_type = value.r#type();
-
-                expected_type.check(&actual_type)?;
-            }
-
-            Ok(Value::r#struct(Struct::Tuple {
-                name: expected_name.clone(),
-                fields,
-            }))
-        } else {
-            Err(ConstructError::ExpectedTuple)
-        }
-    }
-
-    pub fn construct_fields(
-        &self,
-        fields: HashMap<Identifier, Value>,
-    ) -> Result<Value, ConstructError> {
-        if let StructType::Fields {
-            name: expected_name,
-            fields: expected_fields,
-        } = &self.struct_type
-        {
-            if fields.len() != expected_fields.len() {
-                return Err(ConstructError::FieldCountMismatch);
-            }
-
-            for (field_name, field_value) in fields.iter() {
-                let expected_type = expected_fields.get(field_name).unwrap();
-                let actual_type = field_value.r#type();
-
-                expected_type.check(&actual_type)?;
-            }
-
-            Ok(Value::r#struct(Struct::Fields {
-                name: expected_name.clone(),
-                fields,
-            }))
-        } else {
-            Err(ConstructError::ExpectedFields)
-        }
-    }
-}
-
-#[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
-pub enum ConstructError {
-    FieldCountMismatch,
-    ExpectedUnit,
-    ExpectedTuple,
-    ExpectedFields,
-    TypeConflict(TypeConflict),
-}
-
-impl From<TypeConflict> for ConstructError {
-    fn from(conflict: TypeConflict) -> Self {
-        Self::TypeConflict(conflict)
-    }
-}
-
-impl Display for ConstructError {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self {
-            ConstructError::FieldCountMismatch => write!(f, "Field count mismatch"),
-            ConstructError::ExpectedUnit => write!(f, "Expected unit struct"),
-            ConstructError::ExpectedTuple => write!(f, "Expected tuple struct"),
-            ConstructError::ExpectedFields => write!(f, "Expected fields struct"),
-            ConstructError::TypeConflict(TypeConflict { expected, actual }) => {
-                write!(f, "Type conflict: expected {}, got {}", expected, actual)
-            }
-        }
-    }
-}
--- a/dust-lang/src/context.rs
+++ b/dust-lang/src/context.rs
@ -1,651 +0,0 @@
-//! Garbage-collecting context for variables.
-use std::{
-    collections::HashMap,
-    fmt::{self, Display, Formatter},
-    sync::{
-        atomic::{AtomicUsize, Ordering},
-        Arc, PoisonError, RwLock, RwLockReadGuard, RwLockWriteGuard, Weak,
-    },
-};
-
-use crate::{Constructor, Identifier, StructType, Type, Value};
-
-pub type Associations = HashMap<Identifier, (ContextData, usize)>;
-
-static ID_COUNTER: AtomicUsize = AtomicUsize::new(0);
-
-fn next_id() -> usize {
-    ID_COUNTER.fetch_add(1, Ordering::SeqCst)
-}
-
-/// Garbage-collecting context for variables.
-#[derive(Debug, Clone)]
-pub struct Context {
-    inner: Arc<ContextInner>,
-}
-
-impl Context {
-    pub fn new() -> Self {
-        Self::with_data(HashMap::new())
-    }
-
-    pub fn with_data(data: Associations) -> Self {
-        Self {
-            inner: Arc::new(ContextInner {
-                associations: RwLock::new(data),
-                parent: None,
-                is_immutable: false,
-                id: next_id(),
-            }),
-        }
-    }
-
-    pub fn with_data_immutable(data: Associations) -> Self {
-        Self {
-            inner: Arc::new(ContextInner {
-                associations: RwLock::new(data),
-                parent: None,
-                is_immutable: true,
-                id: next_id(),
-            }),
-        }
-    }
-
-    /// Creates a deep copy of another context.
-    pub fn with_data_from(other: &Self) -> Result<Self, ContextError> {
-        let mut associations = HashMap::new();
-
-        for (identifier, (context_data, position)) in other.inner.associations.read()?.iter() {
-            associations.insert(identifier.clone(), (context_data.clone(), *position));
-        }
-
-        Ok(Self::with_data(associations))
-    }
-
-    pub fn create_child(&self) -> Self {
-        Self {
-            inner: Arc::new(ContextInner {
-                associations: RwLock::new(HashMap::new()),
-                parent: Some(Arc::downgrade(&self.inner)),
-                is_immutable: false,
-                id: next_id(),
-            }),
-        }
-    }
-
-    pub fn id(&self) -> usize {
-        self.inner.id
-    }
-
-    /// Returns the number of associated identifiers in the context.
-    pub fn association_count(&self) -> Result<usize, ContextError> {
-        self.inner.association_count()
-    }
-
-    /// Returns a boolean indicating whether the identifier is in the context.
-    pub fn contains(&self, identifier: &Identifier) -> Result<bool, ContextError> {
-        self.inner.contains(identifier)
-    }
-
-    /// Returns the full ContextData and Span if the context contains the given identifier.
-    pub fn get(
-        &self,
-        identifier: &Identifier,
-    ) -> Result<Option<(ContextData, usize)>, ContextError> {
-        self.inner.get(identifier)
-    }
-
-    /// Returns the type associated with the given identifier.
-    pub fn get_type(&self, identifier: &Identifier) -> Result<Option<Type>, ContextError> {
-        self.inner.get_type(identifier)
-    }
-
-    /// Returns the ContextData associated with the identifier.
-    pub fn get_data(&self, identifier: &Identifier) -> Result<Option<ContextData>, ContextError> {
-        self.inner.get_data(identifier)
-    }
-
-    /// Returns the value associated with the identifier.
-    pub fn get_variable_value(
-        &self,
-        identifier: &Identifier,
-    ) -> Result<Option<Value>, ContextError> {
-        self.inner.get_variable_value(identifier)
-    }
-
-    /// Returns the constructor associated with the identifier.
-    pub fn get_constructor(
-        &self,
-        identifier: &Identifier,
-    ) -> Result<Option<Constructor>, ContextError> {
-        self.inner.get_constructor(identifier)
-    }
-
-    /// Returns the constructor type associated with the identifier.
-    pub fn get_constructor_type(
-        &self,
-        identifier: &Identifier,
-    ) -> Result<Option<StructType>, ContextError> {
-        self.inner.get_constructor_type(identifier)
-    }
-
-    /// Associates an identifier with a variable type, with a position given for garbage collection.
-    pub fn set_variable_type(
-        &self,
-        identifier: Identifier,
-        r#type: Type,
-    ) -> Result<(), ContextError> {
-        self.inner.set_variable_type(identifier, r#type)
-    }
-
-    /// Associates an identifier with a variable value.
-    pub fn set_variable_value(
-        &self,
-        identifier: Identifier,
-        value: Value,
-    ) -> Result<(), ContextError> {
-        self.inner.set_variable_value(identifier, value)
-    }
-
-    /// Associates an identifier with a constructor.
-    pub fn set_constructor(
-        &self,
-        identifier: Identifier,
-        constructor: Constructor,
-    ) -> Result<(), ContextError> {
-        self.inner.set_constructor(identifier, constructor)
-    }
-
-    /// Associates an identifier with a constructor type, with a position given for garbage
-    /// collection.
-    pub fn set_constructor_type(
-        &self,
-        identifier: Identifier,
-        struct_type: StructType,
-    ) -> Result<(), ContextError> {
-        self.inner.set_constructor_type(identifier, struct_type)
-    }
-
-    /// Collects garbage up to the given position, removing all variables with lesser positions.
-    pub fn collect_garbage(&self, position: usize) -> Result<(), ContextError> {
-        self.inner.collect_garbage(position)
-    }
-
-    /// Updates an associated identifier's last known position, allowing it to live longer in the
-    /// program. Returns a boolean indicating whether the identifier was found. If the identifier is
-    /// not found in the current context, the parent context is searched but parent context's
-    /// position is not updated.
-    pub fn set_position(
-        &self,
-        identifier: &Identifier,
-        position: usize,
-    ) -> Result<bool, ContextError> {
-        self.inner.set_position(identifier, position)
-    }
-
-    /// Recovers the context from a poisoned state by recovering data from an error.
-    ///
-    /// This method is not used.
-    pub fn _recover_from_poison(&mut self, recovered: &RwLockReadGuard<Associations>) {
-        log::debug!("Context is recovering from poison error");
-
-        let mut new_associations = HashMap::new();
-
-        for (identifier, (context_data, position)) in recovered.iter() {
-            new_associations.insert(identifier.clone(), (context_data.clone(), *position));
-        }
-
-        self.inner = Arc::new(ContextInner {
-            associations: RwLock::new(new_associations),
-            parent: None,
-            is_immutable: false,
-            id: next_id(),
-        });
-    }
-}
-
-impl Default for Context {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
-#[derive(Debug)]
-pub struct ContextInner {
-    id: usize,
-    associations: RwLock<Associations>,
-    parent: Option<Weak<ContextInner>>,
-    is_immutable: bool,
-}
-
-impl ContextInner {
-    fn parent(&self) -> Option<Arc<ContextInner>> {
-        self.parent.as_ref().and_then(|parent| parent.upgrade())
-    }
-
-    /// Returns the number of associated identifiers in the context.
-    pub fn association_count(&self) -> Result<usize, ContextError> {
-        Ok(self.associations.read()?.len())
-    }
-
-    /// Returns a boolean indicating whether the identifier is in the context.
-    pub fn contains(&self, identifier: &Identifier) -> Result<bool, ContextError> {
-        if self.associations.read()?.contains_key(identifier) {
-            Ok(true)
-        } else if let Some(parent) = &self.parent {
-            if let Some(parent) = parent.upgrade() {
-                parent.contains(identifier)
-            } else {
-                Ok(false)
-            }
-        } else {
-            Ok(false)
-        }
-    }
-
-    /// Returns the full ContextData and Span if the context contains the given identifier.
-    pub fn get(
-        &self,
-        identifier: &Identifier,
-    ) -> Result<Option<(ContextData, usize)>, ContextError> {
-        if let Some((variable_data, position)) = self.associations.read()?.get(identifier) {
-            return Ok(Some((variable_data.clone(), *position)));
-        } else if let Some(parent) = &self.parent {
-            if let Some(parent) = parent.upgrade() {
-                return parent.get(identifier);
-            }
-        }
-
-        Ok(None)
-    }
-
-    /// Returns the type associated with the given identifier.
-    pub fn get_type(&self, identifier: &Identifier) -> Result<Option<Type>, ContextError> {
-        match self.associations.read()?.get(identifier) {
-            Some((ContextData::VariableType(r#type), _)) => return Ok(Some(r#type.clone())),
-            Some((ContextData::VariableValue(value), _)) => return Ok(Some(value.r#type())),
-            Some((ContextData::ConstructorType(struct_type), _)) => {
-                return Ok(Some(Type::Struct(struct_type.clone())))
-            }
-            _ => {}
-        }
-
-        if let Some(parent) = &self.parent {
-            if let Some(parent) = parent.upgrade() {
-                return parent.get_type(identifier);
-            }
-        }
-
-        Ok(None)
-    }
-
-    /// Returns the ContextData associated with the identifier.
-    pub fn get_data(&self, identifier: &Identifier) -> Result<Option<ContextData>, ContextError> {
-        if let Some((variable_data, _)) = self.associations.read()?.get(identifier) {
-            return Ok(Some(variable_data.clone()));
-        } else if let Some(parent) = &self.parent {
-            if let Some(parent) = parent.upgrade() {
-                return parent.get_data(identifier);
-            }
-        }
-
-        Ok(None)
-    }
-
-    /// Returns the value associated with the identifier.
-    pub fn get_variable_value(
-        &self,
-        identifier: &Identifier,
-    ) -> Result<Option<Value>, ContextError> {
-        if let Some((ContextData::VariableValue(value), _)) =
-            self.associations.read()?.get(identifier)
-        {
-            return Ok(Some(value.clone()));
-        } else if let Some(parent) = &self.parent {
-            if let Some(parent) = parent.upgrade() {
-                return parent.get_variable_value(identifier);
-            }
-        }
-
-        Ok(None)
-    }
-
-    /// Returns the constructor associated with the identifier.
-    pub fn get_constructor(
-        &self,
-        identifier: &Identifier,
-    ) -> Result<Option<Constructor>, ContextError> {
-        if let Some((ContextData::Constructor(constructor), _)) =
-            self.associations.read()?.get(identifier)
-        {
-            return Ok(Some(constructor.clone()));
-        } else if let Some(parent) = &self.parent {
-            if let Some(parent) = parent.upgrade() {
-                return parent.get_constructor(identifier);
-            }
-        }
-
-        Ok(None)
-    }
-
-    /// Returns the constructor type associated with the identifier.
-    pub fn get_constructor_type(
-        &self,
-        identifier: &Identifier,
-    ) -> Result<Option<StructType>, ContextError> {
-        let read_associations = self.associations.read()?;
-
-        if let Some((context_data, _)) = read_associations.get(identifier) {
-            return match context_data {
-                ContextData::Constructor(constructor) => Ok(Some(constructor.struct_type.clone())),
-                ContextData::ConstructorType(struct_type) => Ok(Some(struct_type.clone())),
-                _ => Ok(None),
-            };
-        } else if let Some(parent) = &self.parent {
-            if let Some(parent) = parent.upgrade() {
-                return parent.get_constructor_type(identifier);
-            }
-        }
-
-        Ok(None)
-    }
-
-    /// Associates an identifier with a variable type.
-    pub fn set_variable_type(
-        &self,
-        identifier: Identifier,
-        r#type: Type,
-    ) -> Result<(), ContextError> {
-        if self.is_immutable {
-            return Err(ContextError::CannotMutateImmutableContext);
-        }
-
-        log::trace!("Setting {identifier} to type {type} in context {}", self.id);
-
-        let mut associations = self.associations.write()?;
-        let last_position = associations
-            .get(&identifier)
-            .map(|(_, last_position)| *last_position)
-            .unwrap_or_default();
-
-        associations.insert(
-            identifier,
-            (ContextData::VariableType(r#type), last_position),
-        );
-
-        Ok(())
-    }
-
-    /// Associates an identifier with a variable value.
-    pub fn set_variable_value(
-        &self,
-        identifier: Identifier,
-        value: Value,
-    ) -> Result<(), ContextError> {
-        if self.is_immutable {
-            return Err(ContextError::CannotMutateImmutableContext);
-        }
-
-        log::trace!(
-            "Setting {identifier} to value {value} in context {}",
-            self.id
-        );
-
-        let mut associations = self.associations.write()?;
-        let last_position = associations
-            .get(&identifier)
-            .map(|(_, last_position)| *last_position)
-            .unwrap_or_default();
-
-        associations.insert(
-            identifier,
-            (ContextData::VariableValue(value), last_position),
-        );
-
-        Ok(())
-    }
-
-    /// Associates an identifier with a constructor.
-    pub fn set_constructor(
-        &self,
-        identifier: Identifier,
-        constructor: Constructor,
-    ) -> Result<(), ContextError> {
-        if self.is_immutable {
-            return Err(ContextError::CannotMutateImmutableContext);
-        }
-
-        log::trace!(
-            "Setting {identifier} to constructor {constructor:?} in context {}",
-            self.id
-        );
-
-        let mut associations = self.associations.write()?;
-        let last_position = associations
-            .get(&identifier)
-            .map(|(_, last_position)| *last_position)
-            .unwrap_or_default();
-
-        associations.insert(
-            identifier,
-            (ContextData::Constructor(constructor), last_position),
-        );
-
-        Ok(())
-    }
-
-    /// Associates an identifier with a constructor type, with a position given for garbage
-    /// collection.
-    pub fn set_constructor_type(
-        &self,
-        identifier: Identifier,
-        struct_type: StructType,
-    ) -> Result<(), ContextError> {
-        if self.is_immutable {
-            return Err(ContextError::CannotMutateImmutableContext);
-        }
-
-        log::trace!(
-            "Setting {identifier} to constructor of type {struct_type} in context {}",
-            self.id
-        );
-
-        let mut variables = self.associations.write()?;
-        let last_position = variables
-            .get(&identifier)
-            .map(|(_, last_position)| *last_position)
-            .unwrap_or_default();
-
-        variables.insert(
-            identifier,
-            (ContextData::ConstructorType(struct_type), last_position),
-        );
-
-        Ok(())
-    }
-
-    /// Collects garbage up to the given position, removing all variables with lesser positions.
-    pub fn collect_garbage(&self, position: usize) -> Result<(), ContextError> {
-        if self.is_immutable {
-            return Err(ContextError::CannotMutateImmutableContext);
-        }
-
-        log::trace!("Collecting garbage up to {position} in context {}", self.id);
-
-        let mut variables = self.associations.write()?;
-
-        variables.retain(|identifier, (_, last_used)| {
-            let should_drop = position >= *last_used;
-
-            if should_drop {
-                log::trace!("Removing {identifier} from context {}", self.id);
-            }
-
-            !should_drop
-        });
-        variables.shrink_to_fit();
-
-        Ok(())
-    }
-
-    /// Updates an associated identifier's last known position, allowing it to live longer in the
-    /// program. Returns a boolean indicating whether the identifier was found. If the identifier is
-    /// not found in the current context, the parent context is searched but parent context's
-    /// position is not updated.
-    pub fn set_position(
-        &self,
-        identifier: &Identifier,
-        position: usize,
-    ) -> Result<bool, ContextError> {
-        let found = self.update_position_if_found(identifier, position)?;
-
-        if found {
-            return Ok(true);
-        }
-
-        let found_in_ancestor = if let Some(parent) = &self.parent() {
-            if parent.is_immutable {
-                false
-            } else {
-                parent.update_position_if_found(identifier, position)?
-            }
-        } else {
-            false
-        };
-
-        if found_in_ancestor {
-            return Ok(true);
-        }
-
-        let mut associations = self.associations.write()?;
-
-        log::trace!(
-            "Reserving {identifier} at position {position:?} in context {}",
-            self.id
-        );
-
-        associations.insert(identifier.clone(), (ContextData::Reserved, position));
-
-        Ok(false)
-    }
-
-    fn update_position_if_found(
-        &self,
-        identifier: &Identifier,
-        position: usize,
-    ) -> Result<bool, ContextError> {
-        if self.is_immutable {
-            return Err(ContextError::CannotMutateImmutableContext);
-        }
-
-        let mut associations = self.associations.write()?;
-
-        if let Some((_, last_position)) = associations.get_mut(identifier) {
-            log::trace!(
-                "Updating {identifier}'s last position to {position:?} in context {}",
-                self.id
-            );
-
-            *last_position = position;
-
-            Ok(true)
-        } else {
-            Ok(false)
-        }
-    }
-}
-
-#[derive(Debug, Clone)]
-pub enum ContextData {
-    Constructor(Constructor),
-    ConstructorType(StructType),
-    VariableValue(Value),
-    VariableType(Type),
-    Reserved,
-}
-
-#[derive(Debug, Clone)]
-pub enum ContextError {
-    CannotMutateImmutableContext,
-    PoisonErrorRecovered(Arc<Associations>),
-}
-
-impl From<PoisonError<RwLockWriteGuard<'_, Associations>>> for ContextError {
-    fn from(error: PoisonError<RwLockWriteGuard<'_, Associations>>) -> Self {
-        let associations = error.into_inner().clone();
-
-        Self::PoisonErrorRecovered(Arc::new(associations))
-    }
-}
-
-impl From<PoisonError<RwLockReadGuard<'_, Associations>>> for ContextError {
-    fn from(error: PoisonError<RwLockReadGuard<'_, Associations>>) -> Self {
-        let associations = error.into_inner().clone();
-
-        Self::PoisonErrorRecovered(Arc::new(associations))
-    }
-}
-
-impl PartialEq for ContextError {
-    fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (Self::CannotMutateImmutableContext, Self::CannotMutateImmutableContext) => true,
-            (Self::PoisonErrorRecovered(left), Self::PoisonErrorRecovered(right)) => {
-                Arc::ptr_eq(left, right)
-            }
-            _ => false,
-        }
-    }
-}
-
-impl Display for ContextError {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        match self {
-            Self::CannotMutateImmutableContext => write!(f, "Cannot mutate immutable context"),
-            Self::PoisonErrorRecovered(associations) => {
-                write!(
-                    f,
-                    "Context poisoned with {} associations recovered",
-                    associations.len()
-                )
-            }
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::{parse, Vm};
-
-    use super::*;
-
-    #[test]
-    fn context_removes_variables() {
-        let source = "
-            let x = 5;
-            let y = 10;
-            let z = x + y;
-            z
-        ";
-        let ast = parse(source).unwrap();
-        let context = ast.context.clone();
-
-        assert_eq!(Vm.run(ast), Ok(Some(Value::integer(15))));
-        assert_eq!(context.association_count().unwrap(), 0);
-    }
-
-    #[test]
-    fn garbage_collector_does_not_break_loops() {
-        let source = "
-            let mut z = 0;
-            while z < 10 {
-                z += 1;
-            }
-        ";
-        let ast = parse(source).unwrap();
-        let context = ast.context.clone();
-
-        assert_eq!(Vm.run(ast), Ok(None));
-        assert_eq!(context.association_count().unwrap(), 0);
-    }
-}
--- a/dust-lang/src/core_library.rs
+++ b/dust-lang/src/core_library.rs
@ -1,39 +0,0 @@
-use std::{collections::HashMap, sync::OnceLock};
-
-use crate::{BuiltInFunction, Context, ContextData, Function, Identifier, Value};
-
-static CORE_LIBRARY: OnceLock<Context> = OnceLock::new();
-
-pub fn core_library<'a>() -> &'a Context {
-    CORE_LIBRARY.get_or_init(|| {
-        Context::with_data_immutable(HashMap::from([
-            (
-                Identifier::new("to_string"),
-                (
-                    ContextData::VariableValue(Value::function(Function::BuiltIn(
-                        BuiltInFunction::ToString,
-                    ))),
-                    0,
-                ),
-            ),
-            (
-                Identifier::new("read_line"),
-                (
-                    ContextData::VariableValue(Value::function(Function::BuiltIn(
-                        BuiltInFunction::ReadLine,
-                    ))),
-                    0,
-                ),
-            ),
-            (
-                Identifier::new("write_line"),
-                (
-                    ContextData::VariableValue(Value::function(Function::BuiltIn(
-                        BuiltInFunction::WriteLine,
-                    ))),
-                    0,
-                ),
-            ),
-        ]))
-    })
-}
--- a/dust-lang/src/disassembler.rs
+++ b/dust-lang/src/disassembler.rs
@ -0,0 +1,366 @@
+//! Tool for disassembling chunks into a human-readable format.
+//!
+//! A disassembler can be created by calling [Chunk::disassembler][] or by instantiating one with
+//! [Disassembler::new][].
+//!
+//! # Options
+//!
+//! The disassembler can be customized with the 'styled' option, which will apply ANSI color codes
+//! to the output.
+//!
+//! # Output
+//!
+//! The output of [Disassembler::disassemble] is a string that can be printed to the console or
+//! written to a file. Below is an example of the disassembly for a simple "Hello, world!" program.
+//!
+//! ```text
+//! ┌──────────────────────────────────────────────────────────────────────────────┐
+//! │                             <file name omitted>                              │
+//! │                                                                              │
+//! │                         write_line("Hello, world!")                          │
+//! │                                                                              │
+//! │             3 instructions, 1 constants, 0 locals, returns none              │
+//! │                                                                              │
+//! │                                 Instructions                                 │
+//! │                                 ------------                                 │
+//! │ i  BYTECODE OPERATION             INFO               TYPE         POSITION   │
+//! │--- -------- ------------- -------------------- ---------------- ------------ │
+//! │ 0        03 LOAD_CONSTANT R0 = C0                    str        (11, 26)     │
+//! │ 1   1390117 CALL_NATIVE   write_line(R0)                        (0, 27)      │
+//! │ 2        18 RETURN                                              (27, 27)     │
+//! │┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈│
+//! │                                    Locals                                    │
+//! │                                    ------                                    │
+//! │            i  IDENTIFIER       TYPE       MUTABLE  SCOPE  REGISTER           │
+//! │           --- ---------- ---------------- ------- ------- --------           │
+//! │┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈│
+//! │                                  Constants                                   │
+//! │                                  ---------                                   │
+//! │                              i       VALUE                                   │
+//! │                             --- ---------------                              │
+//! │                              0   Hello, world!                               │
+//! └──────────────────────────────────────────────────────────────────────────────┘
+//! ```
+use std::env::current_exe;
+
+use colored::Colorize;
+
+use crate::{Chunk, ConcreteValue, Local, Value};
+
+const INSTRUCTION_HEADER: [&str; 4] = [
+    "Instructions",
+    "------------",
+    " i  BYTECODE OPERATION             INFO               TYPE        POSITION ",
+    "--- -------- ------------- -------------------- ---------------- ----------",
+];
+
+const CONSTANT_HEADER: [&str; 4] = [
+    "Constants",
+    "---------",
+    " i       VALUE     ",
+    "--- ---------------",
+];
+
+const LOCAL_HEADER: [&str; 4] = [
+    "Locals",
+    "------",
+    " i  IDENTIFIER       TYPE       MUTABLE  SCOPE  REGISTER",
+    "--- ---------- ---------------- ------- ------- --------",
+];
+
+/// Builder that constructs a human-readable representation of a chunk.
+///
+/// See the [module-level documentation](index.html) for more information.
+pub struct Disassembler<'a> {
+    output: String,
+    chunk: &'a Chunk,
+    source: Option<&'a str>,
+
+    // Options
+    styled: bool,
+    indent: usize,
+}
+
+impl<'a> Disassembler<'a> {
+    pub fn new(chunk: &'a Chunk) -> Self {
+        Self {
+            output: String::new(),
+            chunk,
+            source: None,
+            styled: false,
+            indent: 0,
+        }
+    }
+
+    /// The default width of the disassembly output. To correctly align the output, this should
+    /// return the width of the longest line that the disassembler is guaranteed to produce.
+    pub fn default_width() -> usize {
+        let longest_line = INSTRUCTION_HEADER[3];
+
+        longest_line.chars().count().max(80)
+    }
+
+    pub fn source(mut self, source: &'a str) -> Self {
+        self.source = Some(source);
+
+        self
+    }
+
+    pub fn styled(mut self, styled: bool) -> Self {
+        self.styled = styled;
+
+        self
+    }
+
+    pub fn indent(mut self, indent: usize) -> Self {
+        self.indent = indent;
+
+        self
+    }
+
+    fn push(
+        &mut self,
+        text: &str,
+        center: bool,
+        style_bold: bool,
+        style_dim: bool,
+        add_border: bool,
+    ) {
+        let width = Disassembler::default_width();
+        let characters = text.chars().collect::<Vec<char>>();
+        let content_width = if add_border { width - 2 } else { width };
+        let (line_characters, remainder) = characters
+            .split_at_checked(content_width)
+            .unwrap_or((characters.as_slice(), &[]));
+        let (left_pad_length, right_pad_length) = {
+            let extra_space = content_width.saturating_sub(characters.len());
+
+            if center {
+                (extra_space / 2, extra_space / 2 + extra_space % 2)
+            } else {
+                (0, extra_space)
+            }
+        };
+        let content = if style_bold {
+            line_characters
+                .iter()
+                .collect::<String>()
+                .bold()
+                .to_string()
+        } else if style_dim {
+            line_characters
+                .iter()
+                .collect::<String>()
+                .dimmed()
+                .to_string()
+        } else {
+            line_characters.iter().collect::<String>()
+        };
+        let length_before_content = self.output.chars().count();
+
+        for _ in 0..self.indent {
+            self.output.push_str("│   ");
+        }
+
+        if add_border {
+            self.output.push('│');
+        }
+
+        self.output.push_str(&" ".repeat(left_pad_length));
+        self.output.push_str(&content);
+        self.output.push_str(&" ".repeat(right_pad_length));
+
+        let length_after_content = self.output.chars().count();
+        let line_length = length_after_content - length_before_content;
+
+        if line_length < content_width - 1 {
+            self.output
+                .push_str(&" ".repeat(content_width - line_length));
+        }
+
+        if add_border {
+            self.output.push('│');
+        }
+
+        self.output.push('\n');
+
+        if !remainder.is_empty() {
+            self.push(
+                remainder.iter().collect::<String>().as_str(),
+                center,
+                style_bold,
+                style_dim,
+                add_border,
+            );
+        }
+    }
+
+    fn push_header(&mut self, header: &str) {
+        self.push(header, true, self.styled, false, true);
+    }
+
+    fn push_details(&mut self, details: &str) {
+        self.push(details, true, false, false, true);
+    }
+
+    fn push_border(&mut self, border: &str) {
+        self.push(border, false, false, false, false);
+    }
+
+    fn push_empty(&mut self) {
+        self.push("", false, false, false, true);
+    }
+
+    pub fn disassemble(mut self) -> String {
+        let width = Disassembler::default_width();
+        let top_border = "┌".to_string() + &"─".repeat(width - 2) + "┐";
+        let section_border = "│".to_string() + &"┈".repeat(width - 2) + "│";
+        let bottom_border = "└".to_string() + &"─".repeat(width - 2) + "┘";
+        let name_display = self
+            .chunk
+            .name()
+            .map(|identifier| identifier.to_string())
+            .unwrap_or_else(|| {
+                current_exe()
+                    .map(|path| path.to_string_lossy().to_string())
+                    .unwrap_or("Chunk Disassembly".to_string())
+            });
+
+        self.push_border(&top_border);
+        self.push_header(&name_display);
+
+        if let Some(source) = self.source {
+            self.push_empty();
+            self.push_details(
+                &source
+                    .replace("  ", "")
+                    .replace("\n\n", " ")
+                    .replace('\n', " "),
+            );
+            self.push_empty();
+        }
+
+        let info_line = format!(
+            "{} instructions, {} constants, {} locals, returns {}",
+            self.chunk.len(),
+            self.chunk.constants().len(),
+            self.chunk.locals().len(),
+            self.chunk
+                .return_type()
+                .map(|r#type| r#type.to_string())
+                .unwrap_or("none".to_string())
+        );
+
+        self.push(&info_line, true, false, true, true);
+        self.push_empty();
+
+        for line in INSTRUCTION_HEADER {
+            self.push_header(line);
+        }
+
+        for (index, (instruction, position)) in self.chunk.instructions().iter().enumerate() {
+            let bytecode = format!("{:02X}", u32::from(instruction));
+            let operation = instruction.operation().to_string();
+            let info = instruction.disassembly_info(self.chunk);
+            let type_display = instruction
+                .yielded_type(self.chunk)
+                .map(|r#type| {
+                    let type_string = r#type.to_string();
+
+                    if type_string.len() > 16 {
+                        format!("{type_string:.13}...")
+                    } else {
+                        type_string
+                    }
+                })
+                .unwrap_or(String::with_capacity(0));
+            let position = position.to_string();
+
+            let instruction_display = format!(
+                "{index:^3} {bytecode:>8} {operation:13} {info:^20} {type_display:^16} {position:10}"
+            );
+
+            self.push_details(&instruction_display);
+        }
+
+        self.push_border(&section_border);
+
+        for line in LOCAL_HEADER {
+            self.push_header(line);
+        }
+
+        for (
+            index,
+            Local {
+                identifier_index,
+                r#type,
+                scope,
+                register_index,
+                is_mutable: mutable,
+            },
+        ) in self.chunk.locals().iter().enumerate()
+        {
+            let identifier_display = self
+                .chunk
+                .constants()
+                .get(*identifier_index as usize)
+                .map(|value| value.to_string())
+                .unwrap_or_else(|| "unknown".to_string());
+            let type_display = r#type
+                .as_ref()
+                .map(|r#type| {
+                    let type_string = r#type.to_string();
+
+                    if type_string.len() > 16 {
+                        format!("{type_string:.13}...")
+                    } else {
+                        type_string
+                    }
+                })
+                .unwrap_or("unknown".to_string());
+            let local_display = format!(
+                "{index:^3} {identifier_display:10} {type_display:16} {mutable:7} {scope:7} {register_index:8}"
+            );
+
+            self.push_details(&local_display);
+        }
+
+        self.push_border(&section_border);
+
+        for line in CONSTANT_HEADER {
+            self.push_header(line);
+        }
+
+        for (index, value) in self.chunk.constants().iter().enumerate() {
+            let value_display = {
+                let value_string = value.to_string();
+
+                if value_string.len() > 15 {
+                    format!("{value_string:.12}...")
+                } else {
+                    value_string
+                }
+            };
+            let constant_display = format!("{index:^3} {value_display:^15}");
+
+            self.push_details(&constant_display);
+
+            if let Value::Concrete(ConcreteValue::Function(function)) = value {
+                let function_disassembly = function
+                    .chunk()
+                    .disassembler()
+                    .styled(self.styled)
+                    .indent(self.indent + 1)
+                    .disassemble();
+
+                self.output.push_str(&function_disassembly);
+            }
+        }
+
+        self.push_border(&bottom_border);
+
+        let _ = self.output.trim_end_matches('\n');
+
+        self.output
+    }
+}
--- a/dust-lang/src/dust_error.rs
+++ b/dust-lang/src/dust_error.rs
@ -1,167 +1,53 @@
-//! Top-level error handling for the Dust language.
+//! Top-level Dust errors with source code annotations.
 use annotate_snippets::{Level, Renderer, Snippet};
-use std::fmt::Display;

-use crate::{AnalysisError, ContextError, LexError, ParseError, RuntimeError};
+use crate::{vm::VmError, CompileError, Span};

-/// An error that occurred during the execution of the Dust language and its
-/// corresponding source code.
-#[derive(Debug, Clone, PartialEq)]
+/// A top-level error that can occur during the execution of Dust code.
+///
+/// This error can display nicely formatted messages with source code annotations.
+#[derive(Debug, PartialEq)]
 pub enum DustError<'src> {
-    ContextError(ContextError),
+    Compile {
+        error: CompileError,
+        source: &'src str,
+    },
    Runtime {
-        runtime_error: RuntimeError,
+        error: VmError,
        source: &'src str,
    },
-    Analysis {
-        analysis_errors: Vec<AnalysisError>,
-        source: &'src str,
-    },
-    Parse {
-        parse_error: ParseError,
-        source: &'src str,
-    },
-    Lex {
-        lex_error: LexError,
-        source: &'src str,
-    },
-}
-
-impl<'src> From<ContextError> for DustError<'src> {
-    fn from(error: ContextError) -> Self {
-        Self::ContextError(error)
-    }
 }

 impl<'src> DustError<'src> {
-    pub fn runtime(runtime_error: RuntimeError, source: &'src str) -> Self {
-        DustError::Runtime {
-            runtime_error,
-            source,
-        }
-    }
-
-    pub fn analysis<T: Into<Vec<AnalysisError>>>(analysis_errors: T, source: &'src str) -> Self {
-        DustError::Analysis {
-            analysis_errors: analysis_errors.into(),
-            source,
-        }
-    }
-
-    pub fn parse(parse_error: ParseError, source: &'src str) -> Self {
-        DustError::Parse {
-            parse_error,
-            source,
-        }
-    }
-
-    pub fn lex(lex_error: LexError, source: &'src str) -> Self {
-        DustError::Lex { lex_error, source }
-    }
-
-    pub fn title(&self) -> &'static str {
-        match self {
-            DustError::ContextError(_) => "Context error",
-            DustError::Runtime { .. } => "Runtime error",
-            DustError::Analysis { .. } => "Analysis error",
-            DustError::Parse { .. } => "Parse error",
-            DustError::Lex { .. } => "Lex error",
-        }
-    }
-
-    pub fn source(&self) -> &'src str {
-        match self {
-            DustError::ContextError(_) => "",
-            DustError::Runtime { source, .. } => source,
-            DustError::Analysis { source, .. } => source,
-            DustError::Parse { source, .. } => source,
-            DustError::Lex { source, .. } => source,
-        }
-    }
-
    pub fn report(&self) -> String {
        let mut report = String::new();
        let renderer = Renderer::styled();

        match self {
-            DustError::ContextError(_) => {
-                let message = Level::Error.title("Context error");
-
-                report.push_str(&renderer.render(message).to_string());
-            }
-            DustError::Runtime {
-                runtime_error,
-                source,
-            } => {
-                let error = runtime_error.root_error();
+            DustError::Runtime { error, source } => {
                let position = error.position();
-                let label = error.to_string();
-                let message = Level::Error
-                    .title("Runtime error")
-                    .snippet(
+                let label = format!("{}: {}", VmError::title(), error.description());
+                let details = error
+                    .details()
+                    .unwrap_or_else(|| "While running this code".to_string());
+                let message = Level::Error.title(&label).snippet(
                    Snippet::source(source)
-                            .fold(true)
-                            .annotation(Level::Error.span(position.0..position.1).label(&label)),
-                    )
-                    .footer(
-                        Level::Error
-                            .title("This error occured during the execution of the Dust program."),
+                        .fold(false)
+                        .annotation(Level::Error.span(position.0..position.1).label(&details)),
                );

                report.push_str(&renderer.render(message).to_string());
-                report.push_str("\n\n");
            }
-            DustError::Analysis {
-                analysis_errors,
-                source,
-            } => {
-                for error in analysis_errors {
+            DustError::Compile { error, source } => {
                let position = error.position();
-                    let label = error.to_string();
-                    let message =
-                        Level::Warning
-                            .title("Analysis error")
-                            .snippet(Snippet::source(source).fold(true).annotation(
-                                Level::Warning.span(position.0..position.1).label(&label),
-                            ))
-                            .footer(
-                                Level::Warning
-                                    .title("This error was found without running the program."),
-                            );
-
-                    report.push_str(&renderer.render(message).to_string());
-                    report.push_str("\n\n");
-                }
-            }
-            DustError::Parse {
-                parse_error,
-                source,
-            } => {
-                if let ParseError::Lex(lex_error) = parse_error {
-                    let lex_error_report = DustError::lex(lex_error.clone(), source).report();
-
-                    report.push_str(&lex_error_report);
-
-                    return report;
-                }
-
-                let position = parse_error.position();
-                let label = parse_error.to_string();
-                let message = Level::Error.title("Parse error").snippet(
+                let label = format!("{}: {}", CompileError::title(), error.description());
+                let details = error
+                    .details()
+                    .unwrap_or_else(|| "While parsing this code".to_string());
+                let message = Level::Error.title(&label).snippet(
                    Snippet::source(source)
-                        .fold(true)
-                        .annotation(Level::Error.span(position.0..position.1).label(&label)),
-                );
-
-                report.push_str(&renderer.render(message).to_string());
-            }
-            DustError::Lex { lex_error, source } => {
-                let position = lex_error.position();
-                let label = lex_error.to_string();
-                let message = Level::Error.title("Lex error").snippet(
-                    Snippet::source(source)
-                        .fold(true)
-                        .annotation(Level::Error.span(position.0..position.1).label(&label)),
+                        .fold(false)
+                        .annotation(Level::Error.span(position.0..position.1).label(&details)),
                );

                report.push_str(&renderer.render(message).to_string());
@ -172,22 +58,9 @@ impl<'src> DustError<'src> {
    }
 }

-impl Display for DustError<'_> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        match self {
-            DustError::ContextError(context_error) => write!(f, "{context_error}"),
-            DustError::Runtime { runtime_error, .. } => write!(f, "{runtime_error}"),
-            DustError::Analysis {
-                analysis_errors, ..
-            } => {
-                for error in analysis_errors {
-                    write!(f, "{error} ")?;
-                }
-
-                Ok(())
-            }
-            DustError::Parse { parse_error, .. } => write!(f, "{parse_error}"),
-            DustError::Lex { lex_error, .. } => write!(f, "{lex_error}"),
-        }
-    }
+pub trait AnnotatedError {
+    fn title() -> &'static str;
+    fn description(&self) -> &'static str;
+    fn details(&self) -> Option<String>;
+    fn position(&self) -> Span;
 }
--- a/dust-lang/src/evaluation.rs
+++ b/dust-lang/src/evaluation.rs
@ -1,41 +0,0 @@
-use crate::{Constructor, RuntimeError, Span, StructType, Type, Value};
-
-#[derive(Debug, Clone, PartialEq)]
-pub enum Evaluation {
-    Break(Option<Value>),
-    Constructor(Constructor),
-    Return(Option<Value>),
-}
-
-impl Evaluation {
-    pub fn value(self) -> Option<Value> {
-        match self {
-            Evaluation::Return(value_option) => value_option,
-            _ => None,
-        }
-    }
-
-    pub fn expect_value(self, position: Span) -> Result<Value, RuntimeError> {
-        if let Evaluation::Return(Some(value)) = self {
-            Ok(value)
-        } else {
-            Err(RuntimeError::ExpectedValue { position })
-        }
-    }
-}
-
-#[derive(Debug, Clone, PartialEq)]
-pub enum TypeEvaluation {
-    Break(Option<Type>),
-    Constructor(StructType),
-    Return(Option<Type>),
-}
-
-impl TypeEvaluation {
-    pub fn r#type(self) -> Option<Type> {
-        match self {
-            TypeEvaluation::Return(type_option) => type_option,
-            _ => None,
-        }
-    }
-}
--- a/dust-lang/src/formatter.rs
+++ b/dust-lang/src/formatter.rs
@ -0,0 +1,224 @@
+//! Formatting tools
+use std::mem::replace;
+
+use colored::{ColoredString, Colorize, CustomColor};
+
+use crate::{CompileError, DustError, LexError, Lexer, Token};
+
+pub fn format(source: &str, line_numbers: bool, colored: bool) -> Result<String, DustError> {
+    let lexer = Lexer::new(source);
+    let formatted = Formatter::new(lexer)
+        .line_numbers(line_numbers)
+        .colored(colored)
+        .format()
+        .map_err(|error| DustError::Compile {
+            error: CompileError::Lex(error),
+            source,
+        })?;
+
+    Ok(formatted)
+}
+
+#[derive(Debug)]
+pub struct Formatter<'src> {
+    lexer: Lexer<'src>,
+    output_lines: Vec<(String, LineKind, usize)>,
+    next_line: String,
+    indent: usize,
+
+    current_token: Token<'src>,
+    previous_token: Token<'src>,
+
+    // Options
+    line_numbers: bool,
+    colored: bool,
+}
+
+impl<'src> Formatter<'src> {
+    pub fn new(mut lexer: Lexer<'src>) -> Self {
+        let (current_token, _) = lexer.next_token().unwrap();
+
+        Self {
+            lexer,
+            output_lines: Vec::new(),
+            next_line: String::new(),
+            indent: 0,
+            current_token,
+            previous_token: Token::Eof,
+            line_numbers: false,
+            colored: false,
+        }
+    }
+
+    pub fn line_numbers(mut self, line_numbers: bool) -> Self {
+        self.line_numbers = line_numbers;
+
+        self
+    }
+
+    pub fn colored(mut self, colored: bool) -> Self {
+        self.colored = colored;
+
+        self
+    }
+
+    pub fn format(&mut self) -> Result<String, LexError> {
+        let mut line_kind = LineKind::Empty;
+
+        self.advance()?;
+
+        while self.current_token != Token::Eof {
+            use Token::*;
+
+            if self.current_token.is_expression() && line_kind != LineKind::Assignment {
+                line_kind = LineKind::Expression;
+            }
+
+            match self.current_token {
+                Boolean(boolean) => {
+                    self.push_colored(boolean.red());
+                }
+                Byte(byte) => {
+                    self.push_colored(byte.green());
+                }
+                Character(character) => {
+                    self.push_colored(
+                        character
+                            .to_string()
+                            .custom_color(CustomColor::new(225, 150, 150)),
+                    );
+                }
+                Float(float) => {
+                    self.push_colored(float.yellow());
+                }
+                Identifier(identifier) => {
+                    self.push_colored(identifier.blue());
+                    self.next_line.push(' ');
+                }
+                Integer(integer) => {
+                    self.push_colored(integer.cyan());
+                }
+                String(string) => {
+                    self.push_colored(string.magenta());
+                }
+                LeftCurlyBrace => {
+                    self.next_line.push_str(self.current_token.as_str());
+                    self.commit_line(LineKind::OpenBlock);
+
+                    self.indent += 1;
+                }
+                RightCurlyBrace => {
+                    self.commit_line(LineKind::CloseBlock);
+                    self.next_line.push_str(self.current_token.as_str());
+
+                    self.indent -= 1;
+                }
+                Semicolon => {
+                    if line_kind != LineKind::Assignment {
+                        line_kind = LineKind::Statement;
+                    }
+
+                    self.next_line.push_str(self.current_token.as_str());
+                    self.commit_line(line_kind);
+                }
+                Let => {
+                    line_kind = LineKind::Assignment;
+
+                    self.push_colored(self.current_token.as_str().bold());
+                    self.next_line.push(' ');
+                }
+                Break | Loop | Return | While => {
+                    line_kind = LineKind::Statement;
+
+                    self.push_colored(self.current_token.as_str().bold());
+                    self.next_line.push(' ');
+                }
+                token => {
+                    self.next_line.push_str(token.as_str());
+                    self.next_line.push(' ');
+                }
+            }
+        }
+
+        let mut previous_index = 0;
+        let mut current_index = 1;
+
+        while current_index < self.output_lines.len() {
+            let (_, previous, _) = &self.output_lines[previous_index];
+            let (_, current, _) = &self.output_lines[current_index];
+
+            match (previous, current) {
+                (LineKind::Empty, _)
+                | (_, LineKind::Empty)
+                | (LineKind::OpenBlock, _)
+                | (_, LineKind::CloseBlock) => {}
+                (left, right) if left == right => {}
+                _ => {
+                    self.output_lines
+                        .insert(current_index, ("".to_string(), LineKind::Empty, 0));
+                }
+            }
+
+            previous_index += 1;
+            current_index += 1;
+        }
+
+        let formatted = String::with_capacity(
+            self.output_lines
+                .iter()
+                .fold(0, |total, (line, _, _)| total + line.len()),
+        );
+
+        Ok(self.output_lines.iter().enumerate().fold(
+            formatted,
+            |acc, (index, (line, _, indent))| {
+                let index = if index == 0 {
+                    format!("{:<3}| ", index + 1).dimmed()
+                } else {
+                    format!("\n{:<3}| ", index + 1).dimmed()
+                };
+                let left_pad = "    ".repeat(*indent);
+
+                format!("{}{}{}{}", acc, index, left_pad, line)
+            },
+        ))
+    }
+
+    fn advance(&mut self) -> Result<(), LexError> {
+        if self.lexer.is_eof() {
+            return Ok(());
+        }
+
+        let (new_token, position) = self.lexer.next_token()?;
+
+        log::info!(
+            "Parsing {} at {}",
+            new_token.to_string().bold(),
+            position.to_string()
+        );
+
+        self.previous_token = replace(&mut self.current_token, new_token);
+
+        Ok(())
+    }
+
+    fn push_colored(&mut self, colored: ColoredString) {
+        self.next_line.push_str(&format!("{}", colored));
+    }
+
+    fn commit_line(&mut self, line_kind: LineKind) {
+        self.output_lines
+            .push((self.next_line.clone(), line_kind, self.indent));
+        self.next_line.clear();
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum LineKind {
+    Empty,
+    Assignment,
+    Expression,
+    Statement,
+    OpenBlock,
+    CloseBlock,
+}
--- a/dust-lang/src/identifier.rs
+++ b/dust-lang/src/identifier.rs
@ -1,137 +0,0 @@
-//! Key used to identify a value or type.
-//!
-//! Identifiers are used to uniquely identify values and types in Dust programs. They are
-//! cached to avoid duplication. This means that two identifiers with the same text are the same
-//! object in memory.
-//!
-//! # Examples
-//! ```
-//! # use dust_lang::Identifier;
-//! let foo = Identifier::new("foo");
-//! let also_foo = Identifier::new("foo");
-//! let another_foo = Identifier::new("foo");
-//!
-//! assert_eq!(foo.strong_count(), 4); // One for each of the above and one for the cache.
-//! ```
-use std::{
-    collections::HashMap,
-    fmt::{self, Display, Formatter},
-    hash::Hash,
-    sync::{Arc, OnceLock, RwLock},
-};
-
-use serde::{de::Visitor, Deserialize, Serialize};
-
-/// In-use identifiers.
-static IDENTIFIER_CACHE: OnceLock<RwLock<HashMap<String, Identifier>>> = OnceLock::new();
-
-/// Returns the identifier cache.
-fn identifier_cache<'a>() -> &'a RwLock<HashMap<String, Identifier>> {
-    IDENTIFIER_CACHE.get_or_init(|| RwLock::new(HashMap::new()))
-}
-
-/// Key used to identify a value or type.
-///
-/// See the [module-level documentation](index.html) for more information.
-#[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)]
-pub struct Identifier(Arc<String>);
-
-impl Identifier {
-    /// Creates a new identifier or returns a clone of an existing one from a cache.
-    pub fn new<T: ToString>(text: T) -> Self {
-        let string = text.to_string();
-        let mut cache = identifier_cache().write().unwrap();
-
-        if let Some(old) = cache.get(&string) {
-            old.clone()
-        } else {
-            let new = Identifier(Arc::new(string.clone()));
-
-            cache.insert(string, new.clone());
-
-            new
-        }
-    }
-
-    pub fn as_str(&self) -> &str {
-        self.0.as_str()
-    }
-
-    pub fn strong_count(&self) -> usize {
-        Arc::strong_count(&self.0)
-    }
-}
-
-impl From<String> for Identifier {
-    fn from(string: String) -> Self {
-        Identifier::new(string)
-    }
-}
-
-impl From<&str> for Identifier {
-    fn from(slice: &str) -> Self {
-        Identifier::new(slice)
-    }
-}
-
-impl Display for Identifier {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "{}", self.0)
-    }
-}
-
-impl Serialize for Identifier {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: serde::Serializer,
-    {
-        serializer.serialize_str(self.0.as_str())
-    }
-}
-
-impl<'de> Deserialize<'de> for Identifier {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: serde::Deserializer<'de>,
-    {
-        deserializer.deserialize_identifier(IdentifierVisitor)
-    }
-}
-
-struct IdentifierVisitor;
-
-impl<'de> Visitor<'de> for IdentifierVisitor {
-    type Value = Identifier;
-
-    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-        formatter.write_str("a UTF-8 string")
-    }
-
-    fn visit_char<E>(self, v: char) -> Result<Self::Value, E>
-    where
-        E: serde::de::Error,
-    {
-        self.visit_str(v.encode_utf8(&mut [0u8; 4]))
-    }
-
-    fn visit_str<E>(self, v: &str) -> Result<Self::Value, E>
-    where
-        E: serde::de::Error,
-    {
-        Ok(Identifier::new(v))
-    }
-
-    fn visit_borrowed_str<E>(self, v: &'de str) -> Result<Self::Value, E>
-    where
-        E: serde::de::Error,
-    {
-        self.visit_str(v)
-    }
-
-    fn visit_string<E>(self, v: String) -> Result<Self::Value, E>
-    where
-        E: serde::de::Error,
-    {
-        self.visit_str(&v)
-    }
-}
--- a/dust-lang/src/instruction.rs
+++ b/dust-lang/src/instruction.rs
@ -0,0 +1,902 @@
+//! An operation and its arguments for the Dust virtual machine.
+//!
+//! Each instruction is a 32-bit unsigned integer that is divided into five fields:
+//! - Bits 0-6: The operation code.
+//! - Bit 7: A flag indicating whether the B argument is a constant.
+//! - Bit 8: A flag indicating whether the C argument is a constant.
+//! - Bits 9-16: The A argument,
+//! - Bits 17-24: The B argument.
+//! - Bits 25-32: The C argument.
+//!
+//! Be careful when working with instructions directly. When modifying an instruction, be sure to
+//! account for the fact that setting the A, B, or C arguments to 0 will have no effect. It is
+//! usually best to remove instructions and insert new ones in their place instead of mutating them.
+
+use serde::{Deserialize, Serialize};
+
+use crate::{Chunk, NativeFunction, Operation, Type};
+
+/// An operation and its arguments for the Dust virtual machine.
+///
+/// See the [module-level documentation](index.html) for more information.
+#[derive(Debug, Clone, Copy, Eq, PartialEq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+pub struct Instruction(u32);
+
+impl Instruction {
+    pub fn with_operation(operation: Operation) -> Instruction {
+        Instruction(operation as u32)
+    }
+
+    pub fn r#move(to_register: u8, from_register: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Move as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(from_register);
+
+        instruction
+    }
+
+    pub fn close(from_register: u8, to_register: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Close as u32);
+
+        instruction.set_b(from_register);
+        instruction.set_c(to_register);
+
+        instruction
+    }
+
+    pub fn load_boolean(to_register: u8, value: bool, skip: bool) -> Instruction {
+        let mut instruction = Instruction(Operation::LoadBoolean as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b_to_boolean(value);
+        instruction.set_c_to_boolean(skip);
+
+        instruction
+    }
+
+    pub fn load_constant(to_register: u8, constant_index: u8, skip: bool) -> Instruction {
+        let mut instruction = Instruction(Operation::LoadConstant as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(constant_index);
+        instruction.set_c_to_boolean(skip);
+
+        instruction
+    }
+
+    pub fn load_list(to_register: u8, start_register: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::LoadList as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(start_register);
+
+        instruction
+    }
+
+    pub fn load_self(to_register: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::LoadSelf as u32);
+
+        instruction.set_a(to_register);
+
+        instruction
+    }
+
+    pub fn define_local(to_register: u8, local_index: u8, is_mutable: bool) -> Instruction {
+        let mut instruction = Instruction(Operation::DefineLocal as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(local_index);
+        instruction.set_c(if is_mutable { 1 } else { 0 });
+
+        instruction
+    }
+
+    pub fn get_local(to_register: u8, local_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::GetLocal as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(local_index);
+
+        instruction
+    }
+
+    pub fn set_local(from_register: u8, local_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::SetLocal as u32);
+
+        instruction.set_a(from_register);
+        instruction.set_b(local_index);
+
+        instruction
+    }
+
+    pub fn add(to_register: u8, left_index: u8, right_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Add as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(left_index);
+        instruction.set_c(right_index);
+
+        instruction
+    }
+
+    pub fn subtract(to_register: u8, left_index: u8, right_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Subtract as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(left_index);
+        instruction.set_c(right_index);
+
+        instruction
+    }
+
+    pub fn multiply(to_register: u8, left_index: u8, right_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Multiply as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(left_index);
+        instruction.set_c(right_index);
+
+        instruction
+    }
+
+    pub fn divide(to_register: u8, left_index: u8, right_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Divide as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(left_index);
+        instruction.set_c(right_index);
+
+        instruction
+    }
+
+    pub fn modulo(to_register: u8, left_index: u8, right_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Modulo as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(left_index);
+        instruction.set_c(right_index);
+
+        instruction
+    }
+
+    pub fn test(to_register: u8, test_value: bool) -> Instruction {
+        let mut instruction = Instruction(Operation::Test as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_c_to_boolean(test_value);
+
+        instruction
+    }
+
+    pub fn test_set(to_register: u8, argument_index: u8, test_value: bool) -> Instruction {
+        let mut instruction = Instruction(Operation::TestSet as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(argument_index);
+        instruction.set_c_to_boolean(test_value);
+
+        instruction
+    }
+
+    pub fn equal(comparison_boolean: bool, left_index: u8, right_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Equal as u32);
+
+        instruction.set_a_to_boolean(comparison_boolean);
+        instruction.set_b(left_index);
+        instruction.set_c(right_index);
+
+        instruction
+    }
+
+    pub fn less(comparison_boolean: bool, left_index: u8, right_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Less as u32);
+
+        instruction.set_a_to_boolean(comparison_boolean);
+        instruction.set_b(left_index);
+        instruction.set_c(right_index);
+
+        instruction
+    }
+
+    pub fn less_equal(comparison_boolean: bool, left_index: u8, right_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::LessEqual as u32);
+
+        instruction.set_a_to_boolean(comparison_boolean);
+        instruction.set_b(left_index);
+        instruction.set_c(right_index);
+
+        instruction
+    }
+
+    pub fn negate(to_register: u8, from_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Negate as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(from_index);
+
+        instruction
+    }
+
+    pub fn not(to_register: u8, from_index: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Not as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(from_index);
+
+        instruction
+    }
+
+    pub fn jump(jump_offset: u8, is_positive: bool) -> Instruction {
+        let mut instruction = Instruction(Operation::Jump as u32);
+
+        instruction.set_b(jump_offset);
+        instruction.set_c_to_boolean(is_positive);
+
+        instruction
+    }
+
+    pub fn call(to_register: u8, function_register: u8, argument_count: u8) -> Instruction {
+        let mut instruction = Instruction(Operation::Call as u32);
+
+        instruction.set_a(to_register);
+        instruction.set_b(function_register);
+        instruction.set_c(argument_count);
+
+        instruction
+    }
+
+    pub fn call_native(
+        to_register: u8,
+        native_fn: NativeFunction,
+        argument_count: u8,
+    ) -> Instruction {
+        let mut instruction = Instruction(Operation::CallNative as u32);
+        let native_fn_byte = native_fn as u8;
+
+        instruction.set_a(to_register);
+        instruction.set_b(native_fn_byte);
+        instruction.set_c(argument_count);
+
+        instruction
+    }
+
+    pub fn r#return(should_return_value: bool) -> Instruction {
+        let mut instruction = Instruction(Operation::Return as u32);
+
+        instruction.set_b_to_boolean(should_return_value);
+
+        instruction
+    }
+
+    pub fn operation(&self) -> Operation {
+        Operation::from((self.0 & 0b0000_0000_0011_1111) as u8)
+    }
+
+    pub fn set_operation(&mut self, operation: Operation) {
+        self.0 |= u8::from(operation) as u32;
+    }
+
+    pub fn data(&self) -> (Operation, u8, u8, u8, bool, bool) {
+        (
+            self.operation(),
+            self.a(),
+            self.b(),
+            self.c(),
+            self.b_is_constant(),
+            self.c_is_constant(),
+        )
+    }
+
+    pub fn a(&self) -> u8 {
+        (self.0 >> 24) as u8
+    }
+
+    pub fn b(&self) -> u8 {
+        (self.0 >> 16) as u8
+    }
+
+    pub fn c(&self) -> u8 {
+        (self.0 >> 8) as u8
+    }
+
+    pub fn a_as_boolean(&self) -> bool {
+        self.a() != 0
+    }
+
+    pub fn b_as_boolean(&self) -> bool {
+        self.b() != 0
+    }
+
+    pub fn c_as_boolean(&self) -> bool {
+        self.c() != 0
+    }
+
+    pub fn set_a_to_boolean(&mut self, boolean: bool) -> &mut Self {
+        self.set_a(if boolean { 1 } else { 0 });
+
+        self
+    }
+
+    pub fn set_b_to_boolean(&mut self, boolean: bool) -> &mut Self {
+        self.set_b(if boolean { 1 } else { 0 });
+
+        self
+    }
+
+    pub fn set_c_to_boolean(&mut self, boolean: bool) -> &mut Self {
+        self.set_c(if boolean { 1 } else { 0 });
+
+        self
+    }
+
+    pub fn set_a(&mut self, to_register: u8) {
+        self.0 |= (to_register as u32) << 24;
+    }
+
+    pub fn set_b(&mut self, argument: u8) {
+        self.0 |= (argument as u32) << 16;
+    }
+
+    pub fn set_c(&mut self, argument: u8) {
+        self.0 |= (argument as u32) << 8;
+    }
+
+    pub fn b_is_constant(&self) -> bool {
+        self.0 & 0b1000_0000 != 0
+    }
+
+    pub fn c_is_constant(&self) -> bool {
+        self.0 & 0b0100_0000 != 0
+    }
+
+    pub fn set_b_is_constant(&mut self) -> &mut Self {
+        self.0 |= 0b1000_0000;
+
+        self
+    }
+
+    pub fn set_c_is_constant(&mut self) -> &mut Self {
+        self.0 |= 0b0100_0000;
+
+        self
+    }
+
+    pub fn yields_value(&self) -> bool {
+        match self.operation() {
+            Operation::Add
+            | Operation::Call
+            | Operation::Divide
+            | Operation::GetLocal
+            | Operation::LoadBoolean
+            | Operation::LoadConstant
+            | Operation::LoadList
+            | Operation::LoadSelf
+            | Operation::Modulo
+            | Operation::Multiply
+            | Operation::Negate
+            | Operation::Not
+            | Operation::Subtract => true,
+            Operation::CallNative => {
+                let native_function = NativeFunction::from(self.b());
+
+                native_function.r#type().return_type.is_some()
+            }
+            _ => false,
+        }
+    }
+
+    pub fn yielded_type(&self, chunk: &Chunk) -> Option<Type> {
+        use Operation::*;
+
+        match self.operation() {
+            Add | Divide | Modulo | Multiply | Subtract => {
+                if self.b_is_constant() {
+                    chunk.get_constant_type(self.b())
+                } else {
+                    chunk.get_register_type(self.b())
+                }
+            }
+            LoadBoolean | Not => Some(Type::Boolean),
+            Negate => {
+                if self.b_is_constant() {
+                    chunk.get_constant_type(self.b())
+                } else {
+                    chunk.get_register_type(self.b())
+                }
+            }
+            LoadConstant => chunk.get_constant_type(self.b()),
+            LoadList => chunk.get_register_type(self.a()),
+            GetLocal => chunk.get_local_type(self.b()),
+            CallNative => {
+                let native_function = NativeFunction::from(self.b());
+
+                native_function.r#type().return_type.map(|boxed| *boxed)
+            }
+            _ => None,
+        }
+    }
+
+    pub fn disassembly_info(&self, chunk: &Chunk) -> String {
+        let format_arguments = || {
+            let first_argument = if self.b_is_constant() {
+                format!("C{}", self.b())
+            } else {
+                format!("R{}", self.b())
+            };
+            let second_argument = if self.c_is_constant() {
+                format!("C{}", self.c())
+            } else {
+                format!("R{}", self.c())
+            };
+
+            (first_argument, second_argument)
+        };
+
+        match self.operation() {
+            Operation::Move => format!("R{} = R{}", self.a(), self.b()),
+            Operation::Close => {
+                let from_register = self.b();
+                let to_register = self.c().saturating_sub(1);
+
+                format!("R{from_register}..=R{to_register}")
+            }
+            Operation::LoadBoolean => {
+                let to_register = self.a();
+                let boolean = self.b_as_boolean();
+                let jump = self.c_as_boolean();
+
+                if jump {
+                    format!("R{to_register} = {boolean} && SKIP")
+                } else {
+                    format!("R{to_register} = {boolean}")
+                }
+            }
+            Operation::LoadConstant => {
+                let register_index = self.a();
+                let constant_index = self.b();
+                let jump = self.c_as_boolean();
+
+                if jump {
+                    format!("R{register_index} = C{constant_index} && SKIP")
+                } else {
+                    format!("R{register_index} = C{constant_index}")
+                }
+            }
+            Operation::LoadList => {
+                let to_register = self.a();
+                let first_index = self.b();
+                let last_index = self.c();
+
+                format!("R{to_register} = [R{first_index}..=R{last_index}]",)
+            }
+            Operation::LoadSelf => {
+                let to_register = self.a();
+                let name = chunk
+                    .name()
+                    .map(|idenifier| idenifier.as_str())
+                    .unwrap_or("self");
+
+                format!("R{to_register} = {name}")
+            }
+            Operation::DefineLocal => {
+                let to_register = self.a();
+                let local_index = self.b();
+                let identifier_display = match chunk.get_identifier(local_index) {
+                    Some(identifier) => identifier.to_string(),
+                    None => "???".to_string(),
+                };
+                let mutable_display = if self.c_as_boolean() { "mut" } else { "" };
+
+                format!("R{to_register} = L{local_index} {mutable_display} {identifier_display}")
+            }
+            Operation::GetLocal => {
+                let local_index = self.b();
+
+                format!("R{} = L{}", self.a(), local_index)
+            }
+            Operation::SetLocal => {
+                let local_index = self.b();
+                let identifier_display = match chunk.get_identifier(local_index) {
+                    Some(identifier) => identifier.to_string(),
+                    None => "???".to_string(),
+                };
+
+                format!("L{} = R{} {}", local_index, self.a(), identifier_display)
+            }
+            Operation::Add => {
+                let to_register = self.a();
+                let (first_argument, second_argument) = format_arguments();
+
+                format!("R{to_register} = {first_argument} + {second_argument}",)
+            }
+            Operation::Subtract => {
+                let to_register = self.a();
+                let (first_argument, second_argument) = format_arguments();
+
+                format!("R{to_register} = {first_argument} - {second_argument}",)
+            }
+            Operation::Multiply => {
+                let to_register = self.a();
+                let (first_argument, second_argument) = format_arguments();
+
+                format!("R{to_register} = {first_argument} * {second_argument}",)
+            }
+            Operation::Divide => {
+                let to_register = self.a();
+                let (first_argument, second_argument) = format_arguments();
+
+                format!("R{to_register} = {first_argument} / {second_argument}",)
+            }
+            Operation::Modulo => {
+                let to_register = self.a();
+                let (first_argument, second_argument) = format_arguments();
+
+                format!("R{to_register} = {first_argument} % {second_argument}",)
+            }
+            Operation::Test => {
+                let to_register = self.a();
+                let test_value = self.c_as_boolean();
+
+                format!("if R{to_register} != {test_value} {{ SKIP }}")
+            }
+            Operation::TestSet => {
+                let to_register = self.a();
+                let argument = format!("R{}", self.b());
+                let test_value = self.c_as_boolean();
+                let bang = if test_value { "" } else { "!" };
+
+                format!("if {bang}R{to_register} {{ R{to_register} = R{argument} }}",)
+            }
+            Operation::Equal => {
+                let comparison_symbol = if self.a_as_boolean() { "==" } else { "!=" };
+
+                let (first_argument, second_argument) = format_arguments();
+
+                format!("if {first_argument} {comparison_symbol} {second_argument} {{ SKIP }}")
+            }
+            Operation::Less => {
+                let comparison_symbol = if self.a_as_boolean() { "<" } else { ">=" };
+                let (first_argument, second_argument) = format_arguments();
+
+                format!("if {first_argument} {comparison_symbol} {second_argument} {{ SKIP }}")
+            }
+            Operation::LessEqual => {
+                let comparison_symbol = if self.a_as_boolean() { "<=" } else { ">" };
+                let (first_argument, second_argument) = format_arguments();
+
+                format!("if {first_argument} {comparison_symbol} {second_argument} {{ SKIP }}")
+            }
+            Operation::Negate => {
+                let to_register = self.a();
+                let argument = if self.b_is_constant() {
+                    format!("C{}", self.b())
+                } else {
+                    format!("R{}", self.b())
+                };
+
+                format!("R{to_register} = -{argument}")
+            }
+            Operation::Not => {
+                let to_register = self.a();
+                let argument = if self.b_is_constant() {
+                    format!("C{}", self.b())
+                } else {
+                    format!("R{}", self.b())
+                };
+
+                format!("R{to_register} = !{argument}")
+            }
+            Operation::Jump => {
+                let jump_distance = self.b();
+                let is_positive = self.c_as_boolean();
+
+                if is_positive {
+                    format!("JUMP +{jump_distance}")
+                } else {
+                    format!("JUMP -{jump_distance}")
+                }
+            }
+            Operation::Call => {
+                let to_register = self.a();
+                let function_register = self.b();
+                let argument_count = self.c();
+
+                let mut output = format!("R{to_register} = R{function_register}(");
+
+                if argument_count != 0 {
+                    let first_argument = function_register + 1;
+
+                    for (index, register) in
+                        (first_argument..first_argument + argument_count).enumerate()
+                    {
+                        if index > 0 {
+                            output.push_str(", ");
+                        }
+
+                        output.push_str(&format!("R{}", register));
+                    }
+                }
+
+                output.push(')');
+
+                output
+            }
+            Operation::CallNative => {
+                let to_register = self.a();
+                let native_function = NativeFunction::from(self.b());
+                let argument_count = self.c();
+                let mut output = String::new();
+                let native_function_name = native_function.as_str();
+
+                if native_function.r#type().return_type.is_some() {
+                    output.push_str(&format!("R{} = {}(", to_register, native_function_name));
+                } else {
+                    output.push_str(&format!("{}(", native_function_name));
+                }
+
+                if argument_count != 0 {
+                    let first_argument = to_register.saturating_sub(argument_count);
+
+                    for (index, register) in (first_argument..to_register).enumerate() {
+                        if index > 0 {
+                            output.push_str(", ");
+                        }
+
+                        output.push_str(&format!("R{}", register));
+                    }
+                }
+
+                output.push(')');
+
+                output
+            }
+            Operation::Return => {
+                let should_return_value = self.b_as_boolean();
+
+                if should_return_value {
+                    "->".to_string()
+                } else {
+                    "".to_string()
+                }
+            }
+        }
+    }
+}
+
+impl From<&Instruction> for u32 {
+    fn from(instruction: &Instruction) -> Self {
+        instruction.0
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn r#move() {
+        let mut instruction = Instruction::r#move(0, 1);
+
+        instruction.set_b_is_constant();
+        instruction.set_c_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::Move);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+        assert!(instruction.b_is_constant());
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn close() {
+        let instruction = Instruction::close(1, 2);
+
+        assert_eq!(instruction.operation(), Operation::Close);
+        assert_eq!(instruction.b(), 1);
+        assert_eq!(instruction.c(), 2);
+    }
+
+    #[test]
+    fn load_boolean() {
+        let instruction = Instruction::load_boolean(4, true, true);
+
+        assert_eq!(instruction.operation(), Operation::LoadBoolean);
+        assert_eq!(instruction.a(), 4);
+        assert!(instruction.a_as_boolean());
+        assert!(instruction.c_as_boolean());
+    }
+
+    #[test]
+    fn load_constant() {
+        let mut instruction = Instruction::load_constant(0, 1, true);
+
+        instruction.set_b_is_constant();
+        instruction.set_c_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::LoadConstant);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+        assert!(instruction.b_is_constant());
+        assert!(instruction.b_is_constant());
+        assert!(instruction.c_as_boolean());
+    }
+
+    #[test]
+    fn load_list() {
+        let instruction = Instruction::load_list(0, 1);
+
+        assert_eq!(instruction.operation(), Operation::LoadList);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+    }
+
+    #[test]
+    fn load_self() {
+        let instruction = Instruction::load_self(10);
+
+        assert_eq!(instruction.operation(), Operation::LoadSelf);
+        assert_eq!(instruction.a(), 10);
+    }
+
+    #[test]
+    fn declare_local() {
+        let mut instruction = Instruction::define_local(0, 1, true);
+
+        instruction.set_b_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::DefineLocal);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+        assert_eq!(instruction.c(), true as u8);
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn add() {
+        let mut instruction = Instruction::add(1, 1, 0);
+
+        instruction.set_b_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::Add);
+        assert_eq!(instruction.a(), 1);
+        assert_eq!(instruction.b(), 1);
+        assert_eq!(instruction.c(), 0);
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn subtract() {
+        let mut instruction = Instruction::subtract(0, 1, 2);
+
+        instruction.set_b_is_constant();
+        instruction.set_c_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::Subtract);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+        assert_eq!(instruction.c(), 2);
+        assert!(instruction.b_is_constant());
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn multiply() {
+        let mut instruction = Instruction::multiply(0, 1, 2);
+
+        instruction.set_b_is_constant();
+        instruction.set_c_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::Multiply);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+        assert_eq!(instruction.c(), 2);
+        assert!(instruction.b_is_constant());
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn divide() {
+        let mut instruction = Instruction::divide(0, 1, 2);
+
+        instruction.set_b_is_constant();
+        instruction.set_c_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::Divide);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+        assert_eq!(instruction.c(), 2);
+        assert!(instruction.b_is_constant());
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn and() {
+        let instruction = Instruction::test(4, true);
+
+        assert_eq!(instruction.operation(), Operation::Test);
+        assert_eq!(instruction.a(), 4);
+        assert!(instruction.c_as_boolean());
+    }
+
+    #[test]
+    fn or() {
+        let instruction = Instruction::test_set(4, 1, true);
+
+        assert_eq!(instruction.operation(), Operation::TestSet);
+        assert_eq!(instruction.a(), 4);
+        assert_eq!(instruction.b(), 1);
+        assert!(instruction.c_as_boolean());
+    }
+
+    #[test]
+    fn equal() {
+        let mut instruction = Instruction::equal(true, 1, 2);
+
+        instruction.set_b_is_constant();
+        instruction.set_c_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::Equal);
+        assert!(instruction.a_as_boolean());
+        assert_eq!(instruction.b(), 1);
+        assert_eq!(instruction.c(), 2);
+        assert!(instruction.b_is_constant());
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn negate() {
+        let mut instruction = Instruction::negate(0, 1);
+
+        instruction.set_b_is_constant();
+        instruction.set_c_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::Negate);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+        assert!(instruction.b_is_constant());
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn not() {
+        let mut instruction = Instruction::not(0, 1);
+
+        instruction.set_b_is_constant();
+        instruction.set_c_is_constant();
+
+        assert_eq!(instruction.operation(), Operation::Not);
+        assert_eq!(instruction.a(), 0);
+        assert_eq!(instruction.b(), 1);
+        assert!(instruction.b_is_constant());
+        assert!(instruction.b_is_constant());
+    }
+
+    #[test]
+    fn jump() {
+        let instruction = Instruction::jump(4, true);
+
+        assert_eq!(instruction.operation(), Operation::Jump);
+
+        assert_eq!(instruction.b(), 4);
+        assert!(instruction.c_as_boolean());
+    }
+
+    #[test]
+    fn call() {
+        let instruction = Instruction::call(1, 3, 4);
+
+        assert_eq!(instruction.operation(), Operation::Call);
+        assert_eq!(instruction.a(), 1);
+        assert_eq!(instruction.b(), 3);
+        assert_eq!(instruction.c(), 4);
+    }
+
+    #[test]
+    fn r#return() {
+        let instruction = Instruction::r#return(true);
+
+        assert_eq!(instruction.operation(), Operation::Return);
+        assert!(instruction.b_as_boolean());
+    }
+}
--- a/dust-lang/src/lexer.rs
+++ b/dust-lang/src/lexer.rs
--- a/dust-lang/src/lib.rs
+++ b/dust-lang/src/lib.rs
@ -1,48 +1,44 @@
-//! The Dust programming language.
-//!
-//! To get started, you can use the `run` function to run a Dust program.
-//!
-//! ```rust
-//! use dust_lang::{run, Value};
-//!
-//! let program = "
-//!     let foo = 21
-//!     let bar = 2
-//!     foo * bar
-//! ";
-//!
-//! let the_answer = run(program).unwrap();
-//!
-//! assert_eq!(the_answer, Some(Value::integer(42)));
-//! ```
-pub mod analyzer;
-pub mod ast;
-pub mod built_in_function;
-pub mod constructor;
-pub mod context;
-pub mod core_library;
+//! The Dust programming language library.
+
+pub mod chunk;
+pub mod compiler;
+pub mod disassembler;
 pub mod dust_error;
-pub mod evaluation;
-pub mod identifier;
+pub mod formatter;
+pub mod instruction;
 pub mod lexer;
-pub mod parser;
+pub mod native_function;
+pub mod operation;
+pub mod optimizer;
 pub mod token;
 pub mod r#type;
 pub mod value;
 pub mod vm;

-pub use analyzer::{analyze, AnalysisError, Analyzer};
-pub use ast::{AbstractSyntaxTree, AstError, Expression, Node, Span, Statement};
-pub use built_in_function::{BuiltInFunction, BuiltInFunctionError};
-pub use constructor::{ConstructError, Constructor};
-pub use context::{Context, ContextData, ContextError};
-pub use core_library::core_library;
-pub use dust_error::DustError;
-pub use evaluation::{Evaluation, TypeEvaluation};
-pub use identifier::Identifier;
-pub use lexer::{lex, LexError, Lexer};
-pub use parser::{parse, ParseError, Parser};
-pub use r#type::*;
-pub use token::{Token, TokenKind, TokenOwned};
-pub use value::*;
-pub use vm::{run, RuntimeError, Vm};
+pub use crate::chunk::{Chunk, ChunkError, Local, Scope};
+pub use crate::compiler::{compile, CompileError, Compiler};
+pub use crate::disassembler::Disassembler;
+pub use crate::dust_error::{AnnotatedError, DustError};
+pub use crate::formatter::{format, Formatter};
+pub use crate::instruction::Instruction;
+pub use crate::lexer::{lex, LexError, Lexer};
+pub use crate::native_function::{NativeFunction, NativeFunctionError};
+pub use crate::operation::Operation;
+pub use crate::optimizer::{optimize, Optimizer};
+pub use crate::r#type::{EnumType, FunctionType, RangeableType, StructType, Type, TypeConflict};
+pub use crate::token::{Token, TokenKind, TokenOwned};
+pub use crate::value::{ConcreteValue, Function, Value, ValueError};
+pub use crate::vm::{run, Vm, VmError};
+
+use std::fmt::Display;
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
+pub struct Span(pub usize, pub usize);
+
+impl Display for Span {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "({}, {})", self.0, self.1)
+    }
+}
--- a/dust-lang/src/native_function.rs
+++ b/dust-lang/src/native_function.rs
@ -0,0 +1,418 @@
+//! Built-in functions that implement extended functionality.
+//!
+//! Native functions are used either to implement features that are not possible to implement in
+//! Dust itself or that are more efficient to implement in Rust.
+use std::{
+    fmt::{self, Display, Formatter},
+    io::{self, stdin, stdout, Write},
+    string::{self},
+};
+
+use serde::{Deserialize, Serialize};
+
+use crate::{
+    AnnotatedError, ConcreteValue, FunctionType, Instruction, Span, Type, Value, Vm, VmError,
+};
+
+macro_rules! define_native_function {
+    ($(($name:ident, $byte:literal, $str:expr, $type:expr)),*) => {
+        /// A dust-native function.
+        ///
+        /// See the [module-level documentation](index.html) for more information.
+        #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
+        pub enum NativeFunction {
+            $(
+                $name = $byte as isize,
+            )*
+        }
+
+        impl NativeFunction {
+            pub fn as_str(&self) -> &'static str {
+                match self {
+                    $(
+                        NativeFunction::$name => $str,
+                    )*
+                }
+            }
+
+            #[allow(clippy::should_implement_trait)]
+            pub fn from_str(string: &str) -> Option<Self> {
+                match string {
+                    $(
+                        $str => Some(NativeFunction::$name),
+                    )*
+                    _ => None,
+                }
+            }
+
+            pub fn r#type(&self) -> FunctionType {
+                match self {
+                    $(
+                        NativeFunction::$name => $type,
+                    )*
+                }
+            }
+
+            pub fn returns_value(&self) -> bool {
+                match self {
+                    $(
+                        NativeFunction::$name => $type.return_type.is_some(),
+                    )*
+                }
+            }
+        }
+
+        impl From<u8> for NativeFunction {
+            fn from(byte: u8) -> Self {
+                match byte {
+                    $(
+                        $byte => NativeFunction::$name,
+                    )*
+                    _ => {
+                        if cfg!(test) {
+                            panic!("Invalid native function byte: {}", byte)
+                        } else {
+                            NativeFunction::Panic
+                        }
+                    }
+                }
+            }
+        }
+
+        impl From<NativeFunction> for u8 {
+            fn from(native_function: NativeFunction) -> Self {
+                match native_function {
+                    $(
+                        NativeFunction::$name => $byte,
+                    )*
+                }
+            }
+        }
+    };
+}
+
+define_native_function! {
+    // Assertion
+    (
+        Assert,
+        0_u8,
+        "assert",
+        FunctionType {
+            type_parameters: None,
+            value_parameters: None,
+            return_type: None
+        }
+    ),
+    // (AssertEqual, 1_u8, "assert_equal", false),
+    // (AssertNotEqual, 2_u8, "assert_not_equal", false),
+    (
+        Panic,
+        3_u8,
+        "panic",
+        FunctionType {
+            type_parameters: None,
+            value_parameters: None,
+            return_type: Some(Box::new(Type::Any))
+        }
+    ),
+
+    // // Type conversion
+    // (Parse, 4_u8, "parse", true),
+    // (ToByte, 5_u8, "to_byte", true),
+    // (ToFloat, 6_u8, "to_float", true),
+    // (ToInteger, 7_u8, "to_integer", true),
+    (
+        ToString,
+        8_u8,
+        "to_string",
+        FunctionType {
+            type_parameters: None,
+            value_parameters: Some(vec![(0, Type::Any)]),
+            return_type: Some(Box::new(Type::String { length: None }))
+        }
+    ),
+
+    // // List and string
+    // (All, 9_u8, "all", true),
+    // (Any, 10_u8, "any", true),
+    // (Append, 11_u8, "append", false),
+    // (Contains, 12_u8, "contains", true),
+    // (Dedup, 13_u8, "dedup", false),
+    // (EndsWith, 14_u8, "ends_with", true),
+    // (Find, 15_u8, "find", true),
+    // (Get, 16_u8, "get", true),
+    // (IndexOf, 17_u8, "index_of", true),
+    // (Length, 18_u8, "length", true),
+    // (Prepend, 19_u8, "prepend", false),
+    // (Replace, 20_u8, "replace", false),
+    // (Set, 21_u8, "set", false),
+    // (StartsWith, 22_u8, "starts_with", true),
+    // (Slice, 23_u8, "slice", true),
+    // (Sort, 24_u8, "sort", false),
+    // (Split, 25_u8, "split", true),
+
+    // // List
+    // (Flatten, 26_u8, "flatten", false),
+    // (Join, 27_u8, "join", true),
+    // (Map, 28_u8, "map", true),
+    // (Reduce, 29_u8, "reduce", true),
+    // (Remove, 30_u8, "remove", false),
+    // (Reverse, 31_u8, "reverse", false),
+    // (Unzip, 32_u8, "unzip", true),
+    // (Zip, 33_u8, "zip", true),
+
+    // // String
+    // (Bytes, 34_u8, "bytes", true),
+    // (CharAt, 35_u8, "char_at", true),
+    // (CharCodeAt, 36_u8, "char_code_at", true),
+    // (Chars, 37_u8, "chars", true),
+    // (Format, 38_u8, "format", true),
+    // (Repeat, 39_u8, "repeat", true),
+    // (SplitAt, 40_u8, "split_at", true),
+    // (SplitLines, 41_u8, "split_lines", true),
+    // (SplitWhitespace, 42_u8, "split_whitespace", true),
+    // (ToLowerCase, 43_u8, "to_lower_case", true),
+    // (ToUpperCase, 44_u8, "to_upper_case", true),
+    // (Trim, 45_u8, "trim", true),
+    // (TrimEnd, 46_u8, "trim_end", true),
+    // (TrimStart, 47_u8, "trim_start", true),
+
+    // // I/O
+    // // Read
+    // (Read, 48_u8, "read", true),
+    // (ReadFile, 49_u8, "read_file", true),
+    (
+        ReadLine,
+        50_u8,
+        "read_line",
+        FunctionType {
+            type_parameters: None,
+            value_parameters: None,
+            return_type: Some(Box::new(Type::String { length: None }))
+        }
+    ),
+    // (ReadTo, 51_u8, "read_to", false),
+    // (ReadUntil, 52_u8, "read_until", true),
+    // // Write
+    // (AppendFile, 53_u8, "append_file", false),
+    // (PrependFile, 54_u8, "prepend_file", false),
+    (
+        Write,
+        55_u8,
+        "write",
+        FunctionType {
+            type_parameters: None,
+            value_parameters: Some(vec![(0, Type::String { length: None })]),
+            return_type: None
+        }
+    ),
+    // (WriteFile, 56_u8, "write_file", false),
+    (
+        WriteLine,
+        57_u8,
+        "write_line",
+        FunctionType {
+            type_parameters: None,
+            value_parameters: Some(vec![(0, Type::String { length: None })]),
+            return_type: None
+        }
+    )
+
+    // // Random
+    // (Random, 58_u8, "random", true),
+    // (RandomInRange, 59_u8, "random_in_range", true)
+}
+
+impl NativeFunction {
+    pub fn call(
+        &self,
+        instruction: Instruction,
+        vm: &Vm,
+        position: Span,
+    ) -> Result<Option<Value>, VmError> {
+        let to_register = instruction.a();
+        let argument_count = instruction.c();
+
+        let return_value = match self {
+            NativeFunction::Panic => {
+                let message = if argument_count == 0 {
+                    None
+                } else {
+                    let mut message = String::new();
+
+                    for argument_index in 0..argument_count {
+                        if argument_index != 0 {
+                            message.push(' ');
+                        }
+
+                        let argument = vm.open_register(argument_index, position)?;
+
+                        message.push_str(&argument.to_string());
+                    }
+
+                    Some(message)
+                };
+
+                return Err(VmError::NativeFunction(NativeFunctionError::Panic {
+                    message,
+                    position,
+                }));
+            }
+
+            // Type conversion
+            NativeFunction::ToString => {
+                let mut string = String::new();
+
+                for argument_index in 0..argument_count {
+                    let argument = vm.open_register(argument_index, position)?;
+
+                    string.push_str(&argument.to_string());
+                }
+
+                Some(Value::Concrete(ConcreteValue::String(string)))
+            }
+
+            // I/O
+            NativeFunction::ReadLine => {
+                let mut buffer = String::new();
+
+                stdin().read_line(&mut buffer).map_err(|io_error| {
+                    VmError::NativeFunction(NativeFunctionError::Io {
+                        error: io_error.kind(),
+                        position,
+                    })
+                })?;
+
+                buffer = buffer.trim_end_matches('\n').to_string();
+
+                Some(Value::Concrete(ConcreteValue::String(buffer)))
+            }
+            NativeFunction::Write => {
+                let to_register = instruction.a();
+                let mut stdout = stdout();
+                let map_err = |io_error: io::Error| {
+                    VmError::NativeFunction(NativeFunctionError::Io {
+                        error: io_error.kind(),
+                        position,
+                    })
+                };
+
+                let first_argument = to_register.saturating_sub(argument_count);
+                let last_argument = to_register.saturating_sub(1);
+
+                for argument_index in first_argument..=last_argument {
+                    if argument_index != first_argument {
+                        stdout.write(b" ").map_err(map_err)?;
+                    }
+
+                    let argument_string = vm.open_register(argument_index, position)?.to_string();
+
+                    stdout
+                        .write_all(argument_string.as_bytes())
+                        .map_err(map_err)?;
+                }
+
+                None
+            }
+            NativeFunction::WriteLine => {
+                let mut stdout = stdout();
+                let map_err = |io_error: io::Error| {
+                    VmError::NativeFunction(NativeFunctionError::Io {
+                        error: io_error.kind(),
+                        position,
+                    })
+                };
+
+                let first_index = to_register.saturating_sub(argument_count);
+                let arguments = vm.open_nonempty_registers(first_index..to_register, position)?;
+
+                for (index, argument) in arguments.into_iter().enumerate() {
+                    if index != 0 {
+                        stdout.write(b" ").map_err(map_err)?;
+                    }
+
+                    if let Value::Concrete(ConcreteValue::String(string)) = argument {
+                        let bytes = string.as_bytes();
+
+                        stdout.write_all(bytes).map_err(map_err)?;
+                    } else {
+                        let bytes = argument.to_string().into_bytes();
+
+                        stdout.write_all(&bytes).map_err(map_err)?;
+                    }
+                }
+
+                stdout.write(b"\n").map_err(map_err)?;
+
+                None
+            }
+            _ => todo!(),
+        };
+
+        Ok(return_value)
+    }
+}
+
+impl Display for NativeFunction {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "{}", self.as_str())
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub enum NativeFunctionError {
+    ExpectedArgumentCount {
+        expected: usize,
+        found: usize,
+        position: Span,
+    },
+    Panic {
+        message: Option<String>,
+        position: Span,
+    },
+    Parse {
+        error: string::ParseError,
+        position: Span,
+    },
+    Io {
+        error: io::ErrorKind,
+        position: Span,
+    },
+}
+
+impl AnnotatedError for NativeFunctionError {
+    fn title() -> &'static str {
+        "Native Function Error"
+    }
+
+    fn description(&self) -> &'static str {
+        match self {
+            NativeFunctionError::ExpectedArgumentCount { .. } => {
+                "Expected a different number of arguments"
+            }
+            NativeFunctionError::Panic { .. } => "Explicit panic",
+            NativeFunctionError::Parse { .. } => "Failed to parse value",
+            NativeFunctionError::Io { .. } => "I/O error",
+        }
+    }
+
+    fn details(&self) -> Option<String> {
+        match self {
+            NativeFunctionError::ExpectedArgumentCount {
+                expected, found, ..
+            } => Some(format!("Expected {} arguments, found {}", expected, found)),
+            NativeFunctionError::Panic { message, .. } => message.clone(),
+            NativeFunctionError::Parse { error, .. } => Some(format!("{}", error)),
+            NativeFunctionError::Io { error, .. } => Some(format!("{}", error)),
+        }
+    }
+
+    fn position(&self) -> Span {
+        match self {
+            NativeFunctionError::ExpectedArgumentCount { position, .. } => *position,
+            NativeFunctionError::Panic { position, .. } => *position,
+            NativeFunctionError::Parse { position, .. } => *position,
+            NativeFunctionError::Io { position, .. } => *position,
+        }
+    }
+}
--- a/dust-lang/src/operation.rs
+++ b/dust-lang/src/operation.rs
@ -0,0 +1,110 @@
+//! Part of an [Instruction][crate::Instruction], which can be executed by the Dust virtual machine.
+//!
+//! !!! Warning !!!
+//! The byte values of the operations matter. The seventh and eighth bits must be zero so that the
+//! [Instruction][crate::Instruction] type can use them as flags.
+
+use std::fmt::{self, Display, Formatter};
+
+macro_rules! define_operation {
+    ($(($name:ident, $byte:literal, $str:expr, $type:expr)),*) => {
+        /// Part of an [Instruction][crate::Instruction], which can be executed by the Dust virtual machine.)
+        ///
+        /// See the [module-level documentation](index.html) for more information.
+        #[derive(Clone, Copy, Debug, PartialEq)]
+        pub enum Operation {
+            $(
+                $name = $byte as isize,
+            )*
+        }
+
+        impl From<u8> for Operation {
+            fn from(byte: u8) -> Self {
+                match byte {
+                    $(
+                        $byte => Operation::$name,
+                    )*
+                    _ => {
+                        if cfg!(test) {
+                            panic!("Invalid operation byte: {}", byte)
+                        } else {
+                            Operation::Return
+                        }
+                    }
+                }
+            }
+        }
+
+        impl From<Operation> for u8 {
+            fn from(operation: Operation) -> Self {
+                match operation {
+                    $(
+                        Operation::$name => $byte,
+                    )*
+                }
+            }
+        }
+
+        impl Display for Operation {
+            fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+                match self {
+                    $(
+                        Operation::$name => write!(f, "{}", $str),
+                    )*
+                }
+            }
+        }
+    }
+}
+
+define_operation! {
+    (Move, 0b0000_0000, "MOVE", None),
+    (Close, 0b000_0001, "CLOSE", None),
+    (LoadBoolean, 0b0000_0010, "LOAD_BOOLEAN", None),
+    (LoadConstant, 0b0000_0011, "LOAD_CONSTANT", None),
+    (LoadList, 0b0000_0100, "LOAD_LIST", None),
+    (LoadSelf, 0b0000_0101, "LOAD_SELF", None),
+    (DefineLocal, 0b0000_0110, "DEFINE_LOCAL", None),
+    (GetLocal, 0b0000_0111, "GET_LOCAL", None),
+    (SetLocal, 0b0000_1000, "SET_LOCAL", None),
+    (Add, 0b0000_1001, "ADD", None),
+    (Subtract, 0b0000_1010, "SUBTRACT", None),
+    (Multiply, 0b0000_1011, "MULTIPLY", None),
+    (Divide, 0b0000_1100, "DIVIDE", None),
+    (Modulo, 0b0000_1101, "MODULO", None),
+    (Test, 0b0000_1110, "TEST", None),
+    (TestSet, 0b0000_1111, "TEST_SET", None),
+    (Equal, 0b0001_0000, "EQUAL", None),
+    (Less, 0b0001_0001, "LESS", None),
+    (LessEqual, 0b0001_0010, "LESS_EQUAL", None),
+    (Negate, 0b0001_0011, "NEGATE", None),
+    (Not, 0b0001_0100, "NOT", None),
+    (Jump, 0b0001_0101, "JUMP", None),
+    (Call, 0b0001_0110, "CALL", None),
+    (CallNative, 0b0001_0111, "CALL_NATIVE", None),
+    (Return, 0b0001_1000, "RETURN", None)
+}
+
+impl Operation {
+    pub fn is_math(&self) -> bool {
+        matches!(
+            self,
+            Operation::Add
+                | Operation::Subtract
+                | Operation::Multiply
+                | Operation::Divide
+                | Operation::Modulo
+        )
+    }
+
+    pub fn is_comparison(&self) -> bool {
+        matches!(
+            self,
+            Operation::Equal | Operation::Less | Operation::LessEqual
+        )
+    }
+
+    pub fn is_test(&self) -> bool {
+        matches!(self, Operation::Test | Operation::TestSet)
+    }
+}
--- a/dust-lang/src/optimizer.rs
+++ b/dust-lang/src/optimizer.rs
@ -0,0 +1,96 @@
+//! Tools used by the compiler to optimize a chunk's bytecode.
+use std::{iter::Map, slice::Iter};
+
+use crate::{Instruction, Operation, Span};
+
+type MapToOperation = fn(&(Instruction, Span)) -> Operation;
+
+type OperationIter<'iter> = Map<Iter<'iter, (Instruction, Span)>, MapToOperation>;
+
+/// Performs optimizations on a subset of instructions.
+pub fn optimize(instructions: &mut [(Instruction, Span)]) -> usize {
+    Optimizer::new(instructions).optimize()
+}
+
+/// An instruction optimizer that mutably borrows instructions from a chunk.
+#[derive(Debug, Eq, PartialEq, PartialOrd, Ord)]
+pub struct Optimizer<'chunk> {
+    instructions: &'chunk mut [(Instruction, Span)],
+}
+
+impl<'chunk> Optimizer<'chunk> {
+    /// Creates a new optimizer with a mutable reference to some of a chunk's instructions.
+    pub fn new(instructions: &'chunk mut [(Instruction, Span)]) -> Self {
+        Self { instructions }
+    }
+
+    /// Potentially mutates the instructions to optimize them.
+    pub fn optimize(&mut self) -> usize {
+        let mut optimizations = 0;
+
+        if matches!(
+            self.get_operations(),
+            Some([
+                Operation::Equal | Operation::Less | Operation::LessEqual,
+                Operation::Jump,
+                Operation::LoadBoolean | Operation::LoadConstant,
+                Operation::LoadBoolean | Operation::LoadConstant,
+            ])
+        ) {
+            self.optimize_comparison();
+
+            optimizations += 1;
+        }
+
+        optimizations
+    }
+
+    /// Optimizes a comparison operation.
+    ///
+    /// The instructions must be in the following order:
+    ///     - `Operation::Equal | Operation::Less | Operation::LessEqual`
+    ///     - `Operation::Jump`
+    ///     - `Operation::LoadBoolean | Operation::LoadConstant`
+    ///     - `Operation::LoadBoolean | Operation::LoadConstant`
+    fn optimize_comparison(&mut self) {
+        log::debug!("Optimizing comparison");
+
+        let first_loader_register = {
+            let first_loader = &mut self.instructions[2].0;
+
+            first_loader.set_c_to_boolean(true);
+            first_loader.a()
+        };
+
+        let second_loader = &mut self.instructions[3].0;
+        let mut second_loader_new = Instruction::with_operation(second_loader.operation());
+
+        second_loader_new.set_a(first_loader_register);
+        second_loader_new.set_b(second_loader.b());
+        second_loader_new.set_c(second_loader.c());
+        second_loader_new.set_b_to_boolean(second_loader.b_is_constant());
+        second_loader_new.set_c_to_boolean(second_loader.c_is_constant());
+
+        *second_loader = second_loader_new;
+    }
+
+    fn operations_iter(&self) -> OperationIter {
+        self.instructions
+            .iter()
+            .map(|(instruction, _)| instruction.operation())
+    }
+
+    fn get_operations<const COUNT: usize>(&self) -> Option<[Operation; COUNT]> {
+        if self.instructions.len() < COUNT {
+            return None;
+        }
+
+        let mut n_operations = [Operation::Return; COUNT];
+
+        for (nth, operation) in n_operations.iter_mut().zip(self.operations_iter()) {
+            *nth = operation;
+        }
+
+        Some(n_operations)
+    }
+}
--- a/dust-lang/src/parser.rs
+++ b/dust-lang/src/parser.rs
--- a/dust-lang/src/token.rs
+++ b/dust-lang/src/token.rs
@ -1,16 +1,39 @@
-//! Token and TokenOwned types.
+//! Token, TokenOwned and TokenKind types.
 use std::fmt::{self, Display, Formatter};

 use serde::{Deserialize, Serialize};

-/// Source code token.
-#[derive(Debug, Serialize, Deserialize, PartialEq)]
-pub enum Token<'src> {
-    // End of file
+macro_rules! define_tokens {
+    ($($variant:ident $(($data_type:ty))?),+ $(,)?) => {
+        /// Source token.
+        ///
+        /// This is a borrowed type, i.e. some variants contain references to the source text.
+        #[derive(Debug, Clone, Copy, Eq, PartialEq, PartialOrd, Ord, Default, Serialize, Deserialize)]
+        pub enum Token<'src> {
+            #[default]
            Eof,
+            $(
+                $variant $(($data_type))?,
+            )*
+        }

+        #[derive(Debug, PartialEq, Clone)]
+        /// Data-less representation of a source token.
+        ///
+        /// If a [Token] borrows from the source text, its TokenKind omits the data.
+        pub enum TokenKind {
+            Eof,
+            $(
+                $variant,
+            )*
+        }
+    };
+}
+
+define_tokens! {
    // Hard-coded values
    Boolean(&'src str),
+    Byte(&'src str),
    Character(char),
    Float(&'src str),
    Identifier(&'src str),
@ -23,17 +46,20 @@ pub enum Token<'src> {
    Break,
    Else,
    FloatKeyword,
+    Fn,
    If,
    Int,
    Let,
    Loop,
    Map,
    Mut,
+    Return,
    Str,
    Struct,
    While,

    // Symbols
+    ArrowThin,
    BangEqual,
    Bang,
    Colon,
@ -54,6 +80,7 @@ pub enum Token<'src> {
    Minus,
    MinusEqual,
    Percent,
+    PercentEqual,
    Plus,
    PlusEqual,
    RightCurlyBrace,
@ -61,7 +88,9 @@ pub enum Token<'src> {
    RightSquareBrace,
    Semicolon,
    Slash,
+    SlashEqual,
    Star,
+    StarEqual,
 }

 impl<'src> Token<'src> {
@ -70,16 +99,19 @@ impl<'src> Token<'src> {
        match self {
            Token::Eof => 0,
            Token::Boolean(text) => text.len(),
+            Token::Byte(_) => 3,
            Token::Character(_) => 3,
            Token::Float(text) => text.len(),
            Token::Identifier(text) => text.len(),
            Token::Integer(text) => text.len(),
            Token::String(text) => text.len() + 2,
            Token::Async => 5,
+            Token::ArrowThin => 2,
            Token::Bool => 4,
            Token::Break => 5,
            Token::Else => 4,
            Token::FloatKeyword => 5,
+            Token::Fn => 2,
            Token::If => 2,
            Token::Int => 3,
            Token::Let => 3,
@ -109,25 +141,92 @@ impl<'src> Token<'src> {
            Token::Minus => 1,
            Token::MinusEqual => 2,
            Token::Percent => 1,
+            Token::PercentEqual => 2,
            Token::Plus => 1,
            Token::PlusEqual => 2,
+            Token::Return => 6,
            Token::RightCurlyBrace => 1,
            Token::RightParenthesis => 1,
            Token::RightSquareBrace => 1,
            Token::Semicolon => 1,
            Token::Slash => 1,
+            Token::SlashEqual => 2,
            Token::Star => 1,
+            Token::StarEqual => 2,
+        }
+    }
+
+    pub fn as_str(&self) -> &str {
+        match self {
+            Token::Eof => "",
+            Token::Boolean(text) => text,
+            Token::Byte(text) => text,
+            Token::Character(_) => "character token",
+            Token::Float(text) => text,
+            Token::Identifier(text) => text,
+            Token::Integer(text) => text,
+            Token::String(text) => text,
+            Token::Async => "async",
+            Token::ArrowThin => "->",
+            Token::Bool => "bool",
+            Token::Break => "break",
+            Token::Else => "else",
+            Token::FloatKeyword => "float",
+            Token::Fn => "fn",
+            Token::If => "if",
+            Token::Int => "int",
+            Token::Let => "let",
+            Token::Loop => "loop",
+            Token::Map => "map",
+            Token::Mut => "mut",
+            Token::Str => "str",
+            Token::Struct => "struct",
+            Token::While => "while",
+            Token::BangEqual => "!=",
+            Token::Bang => "!",
+            Token::Colon => ":",
+            Token::Comma => ",",
+            Token::Dot => ".",
+            Token::DoubleAmpersand => "&&",
+            Token::DoubleDot => "..",
+            Token::DoubleEqual => "==",
+            Token::DoublePipe => "||",
+            Token::Equal => "=",
+            Token::Greater => ">",
+            Token::GreaterEqual => ">=",
+            Token::LeftCurlyBrace => "{",
+            Token::LeftParenthesis => "(",
+            Token::LeftSquareBrace => "[",
+            Token::Less => "<",
+            Token::LessEqual => "<=",
+            Token::Minus => "-",
+            Token::MinusEqual => "-=",
+            Token::Percent => "%",
+            Token::PercentEqual => "%=",
+            Token::Plus => "+",
+            Token::PlusEqual => "+=",
+            Token::Return => "return",
+            Token::RightCurlyBrace => "}",
+            Token::RightParenthesis => ")",
+            Token::RightSquareBrace => "]",
+            Token::Semicolon => ";",
+            Token::Slash => "/",
+            Token::SlashEqual => "/=",
+            Token::Star => "*",
+            Token::StarEqual => "*=",
        }
    }

    pub fn to_owned(&self) -> TokenOwned {
        match self {
+            Token::ArrowThin => TokenOwned::ArrowThin,
            Token::Async => TokenOwned::Async,
            Token::BangEqual => TokenOwned::BangEqual,
            Token::Bang => TokenOwned::Bang,
            Token::Bool => TokenOwned::Bool,
            Token::Boolean(boolean) => TokenOwned::Boolean(boolean.to_string()),
            Token::Break => TokenOwned::Break,
+            Token::Byte(byte) => TokenOwned::Byte(byte.to_string()),
            Token::Character(character) => TokenOwned::Character(*character),
            Token::Colon => TokenOwned::Colon,
            Token::Comma => TokenOwned::Comma,
@ -141,6 +240,7 @@ impl<'src> Token<'src> {
            Token::Equal => TokenOwned::Equal,
            Token::Float(float) => TokenOwned::Float(float.to_string()),
            Token::FloatKeyword => TokenOwned::FloatKeyword,
+            Token::Fn => TokenOwned::Fn,
            Token::Greater => TokenOwned::Greater,
            Token::GreaterEqual => TokenOwned::GreaterOrEqual,
            Token::Identifier(text) => TokenOwned::Identifier(text.to_string()),
@ -159,14 +259,18 @@ impl<'src> Token<'src> {
            Token::MinusEqual => TokenOwned::MinusEqual,
            Token::Mut => TokenOwned::Mut,
            Token::Percent => TokenOwned::Percent,
+            Token::PercentEqual => TokenOwned::PercentEqual,
            Token::Plus => TokenOwned::Plus,
            Token::PlusEqual => TokenOwned::PlusEqual,
+            Token::Return => TokenOwned::Return,
            Token::RightCurlyBrace => TokenOwned::RightCurlyBrace,
            Token::RightParenthesis => TokenOwned::RightParenthesis,
            Token::RightSquareBrace => TokenOwned::RightSquareBrace,
            Token::Semicolon => TokenOwned::Semicolon,
            Token::Star => TokenOwned::Star,
+            Token::StarEqual => TokenOwned::StarEqual,
            Token::Slash => TokenOwned::Slash,
+            Token::SlashEqual => TokenOwned::SlashEqual,
            Token::String(text) => TokenOwned::String(text.to_string()),
            Token::Str => TokenOwned::Str,
            Token::Struct => TokenOwned::Struct,
@ -176,12 +280,14 @@ impl<'src> Token<'src> {

    pub fn kind(&self) -> TokenKind {
        match self {
+            Token::ArrowThin => TokenKind::ArrowThin,
            Token::Async => TokenKind::Async,
            Token::BangEqual => TokenKind::BangEqual,
            Token::Bang => TokenKind::Bang,
            Token::Bool => TokenKind::Bool,
            Token::Boolean(_) => TokenKind::Boolean,
            Token::Break => TokenKind::Break,
+            Token::Byte(_) => TokenKind::Byte,
            Token::Character(_) => TokenKind::Character,
            Token::Colon => TokenKind::Colon,
            Token::Comma => TokenKind::Comma,
@ -195,8 +301,9 @@ impl<'src> Token<'src> {
            Token::Equal => TokenKind::Equal,
            Token::Float(_) => TokenKind::Float,
            Token::FloatKeyword => TokenKind::FloatKeyword,
+            Token::Fn => TokenKind::Fn,
            Token::Greater => TokenKind::Greater,
-            Token::GreaterEqual => TokenKind::GreaterOrEqual,
+            Token::GreaterEqual => TokenKind::GreaterEqual,
            Token::Identifier(_) => TokenKind::Identifier,
            Token::If => TokenKind::If,
            Token::Int => TokenKind::Int,
@ -206,21 +313,25 @@ impl<'src> Token<'src> {
            Token::LeftSquareBrace => TokenKind::LeftSquareBrace,
            Token::Let => TokenKind::Let,
            Token::Less => TokenKind::Less,
-            Token::LessEqual => TokenKind::LessOrEqual,
+            Token::LessEqual => TokenKind::LessEqual,
            Token::Loop => TokenKind::Loop,
            Token::Map => TokenKind::Map,
            Token::Minus => TokenKind::Minus,
            Token::MinusEqual => TokenKind::MinusEqual,
            Token::Mut => TokenKind::Mut,
            Token::Percent => TokenKind::Percent,
+            Token::PercentEqual => TokenKind::PercentEqual,
            Token::Plus => TokenKind::Plus,
            Token::PlusEqual => TokenKind::PlusEqual,
+            Token::Return => TokenKind::Return,
            Token::RightCurlyBrace => TokenKind::RightCurlyBrace,
            Token::RightParenthesis => TokenKind::RightParenthesis,
            Token::RightSquareBrace => TokenKind::RightSquareBrace,
            Token::Semicolon => TokenKind::Semicolon,
            Token::Star => TokenKind::Star,
+            Token::StarEqual => TokenKind::StarEqual,
            Token::Slash => TokenKind::Slash,
+            Token::SlashEqual => TokenKind::SlashEqual,
            Token::Str => TokenKind::Str,
            Token::String(_) => TokenKind::String,
            Token::Struct => TokenKind::Struct,
@ -228,55 +339,45 @@ impl<'src> Token<'src> {
        }
    }

-    pub fn is_eof(&self) -> bool {
-        matches!(self, Token::Eof)
-    }
-
-    pub fn precedence(&self) -> u8 {
-        match self {
-            Token::Dot => 9,
-            Token::LeftParenthesis | Token::LeftSquareBrace => 8,
-            Token::Star | Token::Slash | Token::Percent => 7,
-            Token::Minus | Token::Plus => 6,
-            Token::DoubleEqual
+    /// Returns true if the token yields a value, begins an expression or is an expression operator.
+    pub fn is_expression(&self) -> bool {
+        matches!(
+            self,
+            Token::Boolean(_)
+                | Token::Byte(_)
+                | Token::Character(_)
+                | Token::Float(_)
+                | Token::Identifier(_)
+                | Token::Integer(_)
+                | Token::String(_)
+                | Token::Break
+                | Token::If
+                | Token::Return
+                | Token::Map
+                | Token::Loop
+                | Token::Struct
+                | Token::BangEqual
+                | Token::DoubleAmpersand
+                | Token::DoubleEqual
+                | Token::DoublePipe
+                | Token::Equal
+                | Token::Greater
+                | Token::GreaterEqual
+                | Token::LeftCurlyBrace
+                | Token::LeftParenthesis
+                | Token::LeftSquareBrace
                | Token::Less
                | Token::LessEqual
-            | Token::Greater
-            | Token::GreaterEqual => 5,
-            Token::DoubleAmpersand => 4,
-            Token::DoublePipe => 3,
-            Token::DoubleDot => 2,
-            Token::Equal | Token::MinusEqual | Token::PlusEqual => 1,
-            _ => 0,
-        }
-    }
-
-    pub fn is_left_associative(&self) -> bool {
-        matches!(
-            self,
-            Token::Dot
-                | Token::DoubleAmpersand
-                | Token::DoublePipe
-                | Token::Plus
                | Token::Minus
-                | Token::Star
-                | Token::Slash
+                | Token::MinusEqual
                | Token::Percent
-        )
-    }
-
-    pub fn is_right_associative(&self) -> bool {
-        matches!(self, Token::Equal | Token::MinusEqual | Token::PlusEqual)
-    }
-
-    pub fn is_prefix(&self) -> bool {
-        matches!(self, Token::Bang | Token::Minus | Token::Star)
-    }
-
-    pub fn is_postfix(&self) -> bool {
-        matches!(
-            self,
-            Token::Dot | Token::LeftCurlyBrace | Token::LeftParenthesis | Token::LeftSquareBrace
+                | Token::PercentEqual
+                | Token::Plus
+                | Token::PlusEqual
+                | Token::Slash
+                | Token::SlashEqual
+                | Token::Star
+                | Token::StarEqual
        )
    }
 }
@ -284,13 +385,15 @@ impl<'src> Token<'src> {
 impl<'src> Display for Token<'src> {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        match self {
+            Token::ArrowThin => write!(f, "->"),
            Token::Async => write!(f, "async"),
            Token::BangEqual => write!(f, "!="),
            Token::Bang => write!(f, "!"),
            Token::Bool => write!(f, "bool"),
-            Token::Boolean(value) => write!(f, "{}", value),
+            Token::Boolean(value) => write!(f, "{value}"),
            Token::Break => write!(f, "break"),
-            Token::Character(value) => write!(f, "'{}'", value),
+            Token::Byte(value) => write!(f, "{value}"),
+            Token::Character(value) => write!(f, "{value}"),
            Token::Colon => write!(f, ":"),
            Token::Comma => write!(f, ","),
            Token::Dot => write!(f, "."),
@ -301,14 +404,15 @@ impl<'src> Display for Token<'src> {
            Token::Else => write!(f, "else"),
            Token::Eof => write!(f, "EOF"),
            Token::Equal => write!(f, "="),
-            Token::Float(value) => write!(f, "{}", value),
+            Token::Float(value) => write!(f, "{value}"),
            Token::FloatKeyword => write!(f, "float"),
+            Token::Fn => write!(f, "fn"),
            Token::Greater => write!(f, ">"),
            Token::GreaterEqual => write!(f, ">="),
-            Token::Identifier(value) => write!(f, "{}", value),
+            Token::Identifier(value) => write!(f, "{value}"),
            Token::If => write!(f, "if"),
            Token::Int => write!(f, "int"),
-            Token::Integer(value) => write!(f, "{}", value),
+            Token::Integer(value) => write!(f, "{value}"),
            Token::LeftCurlyBrace => write!(f, "{{"),
            Token::LeftParenthesis => write!(f, "("),
            Token::LeftSquareBrace => write!(f, "["),
@ -321,26 +425,30 @@ impl<'src> Display for Token<'src> {
            Token::MinusEqual => write!(f, "-="),
            Token::Mut => write!(f, "mut"),
            Token::Percent => write!(f, "%"),
+            Token::PercentEqual => write!(f, "%="),
            Token::Plus => write!(f, "+"),
            Token::PlusEqual => write!(f, "+="),
+            Token::Return => write!(f, "return"),
            Token::RightCurlyBrace => write!(f, "}}"),
            Token::RightParenthesis => write!(f, ")"),
            Token::RightSquareBrace => write!(f, "]"),
            Token::Semicolon => write!(f, ";"),
            Token::Slash => write!(f, "/"),
+            Token::SlashEqual => write!(f, "/="),
            Token::Star => write!(f, "*"),
+            Token::StarEqual => write!(f, "*="),
            Token::Str => write!(f, "str"),
-            Token::String(value) => write!(f, "\"{}\"", value),
+            Token::String(value) => write!(f, "{value}"),
            Token::Struct => write!(f, "struct"),
            Token::While => write!(f, "while"),
        }
    }
 }

-/// Owned version of `Token`, which owns all the strings.
+/// Owned representation of a source token.
 ///
-/// This is used for errors.
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
+/// If a [Token] borrows from the source text, its TokenOwned omits the data.
+#[derive(Debug, PartialEq, Clone)]
 pub enum TokenOwned {
    Eof,

@ -348,27 +456,31 @@ pub enum TokenOwned {

    // Hard-coded values
    Boolean(String),
+    Byte(String),
    Character(char),
    Float(String),
    Integer(String),
    String(String),

    // Keywords
+    Async,
    Bool,
    Break,
    Else,
    FloatKeyword,
+    Fn,
    If,
    Int,
    Let,
    Loop,
    Map,
    Mut,
+    Return,
    Str,
    While,

    // Symbols
-    Async,
+    ArrowThin,
    Bang,
    BangEqual,
    Colon,
@ -389,6 +501,7 @@ pub enum TokenOwned {
    Minus,
    MinusEqual,
    Percent,
+    PercentEqual,
    Plus,
    PlusEqual,
    RightCurlyBrace,
@ -396,19 +509,23 @@ pub enum TokenOwned {
    RightSquareBrace,
    Semicolon,
    Star,
+    StarEqual,
    Struct,
    Slash,
+    SlashEqual,
 }

 impl Display for TokenOwned {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        match self {
+            TokenOwned::ArrowThin => Token::ArrowThin.fmt(f),
            TokenOwned::Async => Token::Async.fmt(f),
            TokenOwned::Bang => Token::Bang.fmt(f),
            TokenOwned::BangEqual => Token::BangEqual.fmt(f),
            TokenOwned::Bool => Token::Bool.fmt(f),
            TokenOwned::Boolean(boolean) => Token::Boolean(boolean).fmt(f),
            TokenOwned::Break => Token::Break.fmt(f),
+            TokenOwned::Byte(byte) => Token::Byte(byte).fmt(f),
            TokenOwned::Character(character) => Token::Character(*character).fmt(f),
            TokenOwned::Colon => Token::Colon.fmt(f),
            TokenOwned::Comma => Token::Comma.fmt(f),
@ -422,6 +539,7 @@ impl Display for TokenOwned {
            TokenOwned::Equal => Token::Equal.fmt(f),
            TokenOwned::Float(float) => Token::Float(float).fmt(f),
            TokenOwned::FloatKeyword => Token::FloatKeyword.fmt(f),
+            TokenOwned::Fn => Token::Fn.fmt(f),
            TokenOwned::Greater => Token::Greater.fmt(f),
            TokenOwned::GreaterOrEqual => Token::GreaterEqual.fmt(f),
            TokenOwned::Identifier(text) => Token::Identifier(text).fmt(f),
@ -440,14 +558,18 @@ impl Display for TokenOwned {
            TokenOwned::MinusEqual => Token::MinusEqual.fmt(f),
            TokenOwned::Mut => Token::Mut.fmt(f),
            TokenOwned::Percent => Token::Percent.fmt(f),
+            TokenOwned::PercentEqual => Token::PercentEqual.fmt(f),
            TokenOwned::Plus => Token::Plus.fmt(f),
            TokenOwned::PlusEqual => Token::PlusEqual.fmt(f),
+            TokenOwned::Return => Token::Return.fmt(f),
            TokenOwned::RightCurlyBrace => Token::RightCurlyBrace.fmt(f),
            TokenOwned::RightParenthesis => Token::RightParenthesis.fmt(f),
            TokenOwned::RightSquareBrace => Token::RightSquareBrace.fmt(f),
            TokenOwned::Semicolon => Token::Semicolon.fmt(f),
            TokenOwned::Star => Token::Star.fmt(f),
+            TokenOwned::StarEqual => Token::StarEqual.fmt(f),
            TokenOwned::Slash => Token::Slash.fmt(f),
+            TokenOwned::SlashEqual => Token::SlashEqual.fmt(f),
            TokenOwned::Str => Token::Str.fmt(f),
            TokenOwned::String(string) => Token::String(string).fmt(f),
            TokenOwned::Struct => Token::Struct.fmt(f),
@ -456,76 +578,17 @@ impl Display for TokenOwned {
    }
 }

-/// Token representation that holds no data.
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
-pub enum TokenKind {
-    Eof,
-
-    Identifier,
-
-    // Hard-coded values
-    Boolean,
-    Character,
-    Float,
-    Integer,
-    String,
-
-    // Keywords
-    Async,
-    Bool,
-    Break,
-    Else,
-    FloatKeyword,
-    If,
-    Int,
-    Let,
-    Loop,
-    Map,
-    Str,
-    While,
-
-    // Symbols
-    BangEqual,
-    Bang,
-    Colon,
-    Comma,
-    Dot,
-    DoubleAmpersand,
-    DoubleDot,
-    DoubleEqual,
-    DoublePipe,
-    Equal,
-    Greater,
-    GreaterOrEqual,
-    LeftCurlyBrace,
-    LeftParenthesis,
-    LeftSquareBrace,
-    Less,
-    LessOrEqual,
-    Minus,
-    MinusEqual,
-    Mut,
-    Percent,
-    Plus,
-    PlusEqual,
-    RightCurlyBrace,
-    RightParenthesis,
-    RightSquareBrace,
-    Semicolon,
-    Star,
-    Struct,
-    Slash,
-}
-
 impl Display for TokenKind {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        match self {
+            TokenKind::ArrowThin => Token::ArrowThin.fmt(f),
            TokenKind::Async => Token::Async.fmt(f),
            TokenKind::Bang => Token::Bang.fmt(f),
            TokenKind::BangEqual => Token::BangEqual.fmt(f),
            TokenKind::Bool => Token::Bool.fmt(f),
            TokenKind::Boolean => write!(f, "boolean value"),
            TokenKind::Break => Token::Break.fmt(f),
+            TokenKind::Byte => write!(f, "byte value"),
            TokenKind::Character => write!(f, "character value"),
            TokenKind::Colon => Token::Colon.fmt(f),
            TokenKind::Comma => Token::Comma.fmt(f),
@ -539,8 +602,9 @@ impl Display for TokenKind {
            TokenKind::Equal => Token::Equal.fmt(f),
            TokenKind::Float => write!(f, "float value"),
            TokenKind::FloatKeyword => Token::FloatKeyword.fmt(f),
+            TokenKind::Fn => Token::Fn.fmt(f),
            TokenKind::Greater => Token::Greater.fmt(f),
-            TokenKind::GreaterOrEqual => Token::GreaterEqual.fmt(f),
+            TokenKind::GreaterEqual => Token::GreaterEqual.fmt(f),
            TokenKind::Identifier => write!(f, "identifier"),
            TokenKind::If => Token::If.fmt(f),
            TokenKind::Int => Token::Int.fmt(f),
@ -550,102 +614,29 @@ impl Display for TokenKind {
            TokenKind::LeftSquareBrace => Token::LeftSquareBrace.fmt(f),
            TokenKind::Let => Token::Let.fmt(f),
            TokenKind::Less => Token::Less.fmt(f),
-            TokenKind::LessOrEqual => Token::LessEqual.fmt(f),
+            TokenKind::LessEqual => Token::LessEqual.fmt(f),
            TokenKind::Loop => Token::Loop.fmt(f),
            TokenKind::Map => Token::Map.fmt(f),
            TokenKind::Minus => Token::Minus.fmt(f),
            TokenKind::MinusEqual => Token::MinusEqual.fmt(f),
            TokenKind::Mut => Token::Mut.fmt(f),
            TokenKind::Percent => Token::Percent.fmt(f),
+            TokenKind::PercentEqual => Token::PercentEqual.fmt(f),
            TokenKind::Plus => Token::Plus.fmt(f),
            TokenKind::PlusEqual => Token::PlusEqual.fmt(f),
+            TokenKind::Return => Token::Return.fmt(f),
            TokenKind::RightCurlyBrace => Token::RightCurlyBrace.fmt(f),
            TokenKind::RightParenthesis => Token::RightParenthesis.fmt(f),
            TokenKind::RightSquareBrace => Token::RightSquareBrace.fmt(f),
            TokenKind::Semicolon => Token::Semicolon.fmt(f),
            TokenKind::Star => Token::Star.fmt(f),
+            TokenKind::StarEqual => Token::StarEqual.fmt(f),
            TokenKind::Str => Token::Str.fmt(f),
            TokenKind::Slash => Token::Slash.fmt(f),
+            TokenKind::SlashEqual => Token::SlashEqual.fmt(f),
            TokenKind::String => write!(f, "string value"),
            TokenKind::Struct => Token::Struct.fmt(f),
            TokenKind::While => Token::While.fmt(f),
        }
    }
 }
-
-#[cfg(test)]
-pub(crate) mod tests {
-    use super::*;
-
-    pub fn all_tokens<'src>() -> [Token<'src>; 47] {
-        [
-            Token::Async,
-            Token::Bang,
-            Token::BangEqual,
-            Token::Bool,
-            Token::Break,
-            Token::Colon,
-            Token::Comma,
-            Token::Dot,
-            Token::DoubleAmpersand,
-            Token::DoubleDot,
-            Token::DoubleEqual,
-            Token::DoublePipe,
-            Token::Else,
-            Token::Eof,
-            Token::Equal,
-            Token::FloatKeyword,
-            Token::Greater,
-            Token::GreaterEqual,
-            Token::If,
-            Token::Int,
-            Token::LeftCurlyBrace,
-            Token::LeftParenthesis,
-            Token::LeftSquareBrace,
-            Token::Let,
-            Token::Less,
-            Token::LessEqual,
-            Token::Map,
-            Token::Minus,
-            Token::MinusEqual,
-            Token::Mut,
-            Token::Percent,
-            Token::Plus,
-            Token::PlusEqual,
-            Token::RightCurlyBrace,
-            Token::RightParenthesis,
-            Token::RightSquareBrace,
-            Token::Semicolon,
-            Token::Star,
-            Token::Str,
-            Token::Slash,
-            Token::Boolean("true"),
-            Token::Float("0.0"),
-            Token::Integer("0"),
-            Token::String("string"),
-            Token::Identifier("foobar"),
-            Token::Struct,
-            Token::While,
-        ]
-    }
-
-    #[test]
-    fn token_displays() {
-        for token in all_tokens().iter() {
-            let display = token.to_string();
-
-            assert_eq!(display, token.to_owned().to_string());
-
-            if let Token::Boolean(_)
-            | Token::Float(_)
-            | Token::Identifier(_)
-            | Token::Integer(_)
-            | Token::String(_) = token
-            {
-                continue;
-            } else {
-                assert_eq!(display, token.kind().to_string());
-            }
-        }
-    }
-}
--- a/dust-lang/src/type.rs
+++ b/dust-lang/src/type.rs
@ -1,14 +1,4 @@
-//! Description of a kind of value.
-//!
-//! Most types are concrete and specific, the exceptions are the Generic and Any types.
-//!
-//! Generic types are temporary placeholders that describe a type that will be defined later. The
-//! interpreter should use the analysis phase to enforce that all Generic types have a concrete
-//! type assigned to them before the program is run.
-//!
-//! The Any type is used in cases where a value's type does not matter. For example, the standard
-//! library's "length" function does not care about the type of item in the list, only the list
-//! itself. So the input is defined as `[any]`, i.e. `Type::ListOf(Box::new(Type::Any))`.
+//! Value types and conflict handling.
 use std::{
    cmp::Ordering,
    collections::HashMap,
@ -17,11 +7,7 @@ use std::{

 use serde::{Deserialize, Serialize};

-use crate::{Constructor, BuiltInFunction, Identifier};
-
 /// Description of a kind of value.
-///
-/// See the [module documentation](index.html) for more information.
 #[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
 pub enum Type {
    Any,
@ -32,7 +18,7 @@ pub enum Type {
    Float,
    Function(FunctionType),
    Generic {
-        identifier: Identifier,
+        identifier_index: u8,
        concrete_type: Option<Box<Type>>,
    },
    Integer,
@ -45,7 +31,7 @@ pub enum Type {
        item_type: Box<Type>,
    },
    Map {
-        pairs: HashMap<Identifier, Type>,
+        pairs: HashMap<u8, Type>,
    },
    Number,
    Range {
@ -191,20 +177,17 @@ impl Type {
            }
            (
                Type::Function(FunctionType {
-                    name: left_name,
                    type_parameters: left_type_parameters,
                    value_parameters: left_value_parameters,
                    return_type: left_return,
                }),
                Type::Function(FunctionType {
-                    name: right_name,
                    type_parameters: right_type_parameters,
                    value_parameters: right_value_parameters,
                    return_type: right_return,
                }),
            ) => {
-                if left_name != right_name
-                    || left_return != right_return
+                if left_return != right_return
                    || left_type_parameters != right_type_parameters
                    || left_value_parameters != right_value_parameters
                {
@ -233,48 +216,6 @@ impl Type {
            expected: self.clone(),
        })
    }
-
-    pub fn has_field(&self, field: &Identifier) -> bool {
-        match field.as_str() {
-            "to_string" => true,
-            "length" => {
-                matches!(
-                    self,
-                    Type::List { .. }
-                        | Type::ListOf { .. }
-                        | Type::ListEmpty
-                        | Type::Map { .. }
-                        | Type::String { .. }
-                )
-            }
-            "is_even" | "is_odd" => matches!(self, Type::Integer | Type::Float),
-            _ => match self {
-                Type::Struct(StructType::Fields { fields, .. }) => fields.contains_key(field),
-                Type::Map { pairs } => pairs.contains_key(field),
-                _ => false,
-            },
-        }
-    }
-
-    pub fn get_field_type(&self, field: &Identifier) -> Option<Type> {
-        match field.as_str() {
-            "to_string" => Some(BuiltInFunction::ToString.r#type()),
-            "length" => match self {
-                Type::List { .. } => Some(Type::Integer),
-                Type::ListOf { .. } => Some(Type::Integer),
-                Type::ListEmpty => Some(Type::Integer),
-                Type::Map { .. } => Some(Type::Integer),
-                Type::String { .. } => Some(Type::Integer),
-                _ => None,
-            },
-            "is_even" | "is_odd" => Some(Type::Boolean),
-            _ => match self {
-                Type::Struct(StructType::Fields { fields, .. }) => fields.get(field).cloned(),
-                Type::Map { pairs } => pairs.get(field).cloned(),
-                _ => None,
-            },
-        }
-    }
 }

 impl Display for Type {
@ -289,7 +230,10 @@ impl Display for Type {
            Type::Function(function_type) => write!(f, "{function_type}"),
            Type::Generic { concrete_type, .. } => {
                match concrete_type.clone().map(|r#box| *r#box) {
-                    Some(Type::Generic { identifier, .. }) => write!(f, "{identifier}"),
+                    Some(Type::Generic {
+                        identifier_index: identifier,
+                        ..
+                    }) => write!(f, "{identifier}"),
                    Some(concrete_type) => write!(f, "implied to be {concrete_type}"),
                    None => write!(f, "unknown"),
                }
@ -420,9 +364,8 @@ impl Ord for Type {

 #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
 pub struct FunctionType {
-    pub name: Identifier,
-    pub type_parameters: Option<Vec<Identifier>>,
-    pub value_parameters: Option<Vec<(Identifier, Type)>>,
+    pub type_parameters: Option<Vec<u8>>,
+    pub value_parameters: Option<Vec<(u8, Type)>>,
    pub return_type: Option<Box<Type>>,
 }

@ -434,11 +377,11 @@ impl Display for FunctionType {
            write!(f, "<")?;

            for (index, type_parameter) in type_parameters.iter().enumerate() {
-                write!(f, "{type_parameter}")?;
-
-                if index != type_parameters.len() - 1 {
+                if index > 0 {
                    write!(f, ", ")?;
                }
+
+                write!(f, "{type_parameter}")?;
            }

            write!(f, ">")?;
@ -448,11 +391,11 @@ impl Display for FunctionType {

        if let Some(value_parameters) = &self.value_parameters {
            for (index, (identifier, r#type)) in value_parameters.iter().enumerate() {
-                write!(f, "{identifier}: {type}")?;
-
-                if index != value_parameters.len() - 1 {
+                if index > 0 {
                    write!(f, ", ")?;
                }
+
+                write!(f, "{identifier}: {type}")?;
            }
        }

@ -468,31 +411,17 @@ impl Display for FunctionType {

 #[derive(Clone, Debug, Eq, PartialEq, Serialize, Deserialize)]
 pub enum StructType {
-    Unit {
-        name: Identifier,
-    },
-    Tuple {
-        name: Identifier,
-        fields: Vec<Type>,
-    },
-    Fields {
-        name: Identifier,
-        fields: HashMap<Identifier, Type>,
-    },
+    Unit { name: u8 },
+    Tuple { name: u8, fields: Vec<Type> },
+    Fields { name: u8, fields: HashMap<u8, Type> },
 }

 impl StructType {
-    pub fn name(&self) -> &Identifier {
+    pub fn name(&self) -> u8 {
        match self {
-            StructType::Unit { name } => name,
-            StructType::Tuple { name, .. } => name,
-            StructType::Fields { name, .. } => name,
-        }
-    }
-
-    pub fn constructor(&self) -> Constructor {
-        Constructor {
-            struct_type: self.clone(),
+            StructType::Unit { name } => *name,
+            StructType::Tuple { name, .. } => *name,
+            StructType::Fields { name, .. } => *name,
        }
    }
 }
@ -594,7 +523,7 @@ impl Ord for StructType {

 #[derive(Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Serialize, Deserialize)]
 pub struct EnumType {
-    pub name: Identifier,
+    pub name: u8,
    pub variants: Vec<StructType>,
 }

--- a/dust-lang/src/value.rs
+++ b/dust-lang/src/value.rs
--- a/dust-lang/src/vm.rs
+++ b/dust-lang/src/vm.rs
--- a/dust-lang/tests/basic.rs
+++ b/dust-lang/tests/basic.rs
@ -0,0 +1,66 @@
+use dust_lang::*;
+
+#[test]
+fn constant() {
+    let source = "42";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(0, 2)),
+                (Instruction::r#return(true), Span(2, 2))
+            ],
+            vec![Value::integer(42)],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(42))));
+}
+
+#[test]
+fn empty() {
+    let source = "";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![(Instruction::r#return(false), Span(0, 0))],
+            vec![],
+            vec![]
+        ))
+    );
+    assert_eq!(run(source), Ok(None));
+}
+
+#[test]
+fn parentheses_precedence() {
+    let source = "(1 + 2) * 3";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::add(0, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(3, 4)
+                ),
+                (
+                    *Instruction::multiply(1, 0, 2).set_c_is_constant(),
+                    Span(8, 9)
+                ),
+                (Instruction::r#return(true), Span(11, 11)),
+            ],
+            vec![Value::integer(1), Value::integer(2), Value::integer(3)],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(9))));
+}
--- a/dust-lang/tests/comparison.rs
+++ b/dust-lang/tests/comparison.rs
@ -0,0 +1,169 @@
+use dust_lang::*;
+
+#[test]
+fn equal() {
+    let source = "1 == 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 4)
+                ),
+                (Instruction::jump(1, true), Span(2, 4)),
+                (Instruction::load_boolean(0, true, true), Span(2, 4)),
+                (Instruction::load_boolean(0, false, false), Span(2, 4)),
+                (Instruction::r#return(true), Span(6, 6)),
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(false))));
+}
+
+#[test]
+fn greater() {
+    let source = "1 > 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::less_equal(false, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 3)
+                ),
+                (Instruction::jump(1, true), Span(2, 3)),
+                (Instruction::load_boolean(0, true, true), Span(2, 3)),
+                (Instruction::load_boolean(0, false, false), Span(2, 3)),
+                (Instruction::r#return(true), Span(5, 5)),
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(false))));
+}
+
+#[test]
+fn greater_than_or_equal() {
+    let source = "1 >= 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::less(false, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 4)
+                ),
+                (Instruction::jump(1, true), Span(2, 4)),
+                (Instruction::load_boolean(0, true, true), Span(2, 4)),
+                (Instruction::load_boolean(0, false, false), Span(2, 4)),
+                (Instruction::r#return(true), Span(6, 6)),
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(false))));
+}
+
+#[test]
+fn less_than() {
+    let source = "1 < 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::less(true, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 3)
+                ),
+                (Instruction::jump(1, true), Span(2, 3)),
+                (Instruction::load_boolean(0, true, true), Span(2, 3)),
+                (Instruction::load_boolean(0, false, false), Span(2, 3)),
+                (Instruction::r#return(true), Span(5, 5)),
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(true))));
+}
+
+#[test]
+fn less_than_or_equal() {
+    let source = "1 <= 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::less_equal(true, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 4)
+                ),
+                (Instruction::jump(1, true), Span(2, 4)),
+                (Instruction::load_boolean(0, true, true), Span(2, 4)),
+                (Instruction::load_boolean(0, false, false), Span(2, 4)),
+                (Instruction::r#return(true), Span(6, 6)),
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(true))));
+}
+
+#[test]
+fn not_equal() {
+    let source = "1 != 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(false, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 4)
+                ),
+                (Instruction::jump(1, true), Span(2, 4)),
+                (Instruction::load_boolean(0, true, true), Span(2, 4)),
+                (Instruction::load_boolean(0, false, false), Span(2, 4)),
+                (Instruction::r#return(true), Span(6, 6)),
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(true))));
+}
--- a/dust-lang/tests/control_flow.rs
+++ b/dust-lang/tests/control_flow.rs
@ -0,0 +1,420 @@
+use dust_lang::*;
+
+#[test]
+fn equality_assignment_long() {
+    let source = "let a = if 4 == 4 { true } else { false }; a";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 0)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(13, 15)
+                ),
+                (Instruction::jump(1, true), Span(18, 19)),
+                (Instruction::load_boolean(0, true, true), Span(20, 24)),
+                (Instruction::load_boolean(0, false, false), Span(34, 39)),
+                (Instruction::define_local(0, 0, false), Span(4, 5)),
+                (Instruction::get_local(1, 0), Span(43, 44)),
+                (Instruction::r#return(true), Span(44, 44)),
+            ],
+            vec![Value::integer(4), Value::string("a")],
+            vec![Local::new(
+                1,
+                None,
+                false,
+                Scope {
+                    depth: 0,
+                    block_index: 0
+                },
+                0
+            )]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(true))));
+}
+
+#[test]
+fn equality_assignment_short() {
+    let source = "let a = 4 == 4 a";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 0)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(10, 12)
+                ),
+                (Instruction::jump(1, true), Span(10, 12)),
+                (Instruction::load_boolean(0, true, true), Span(10, 12)),
+                (Instruction::load_boolean(0, false, false), Span(10, 12)),
+                (Instruction::define_local(0, 0, false), Span(4, 5)),
+                (Instruction::get_local(1, 0), Span(15, 16)),
+                (Instruction::r#return(true), Span(16, 16)),
+            ],
+            vec![Value::integer(4), Value::string("a")],
+            vec![Local::new(1, None, false, Scope::default(), 0)]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(true))));
+}
+
+#[test]
+fn if_else_assigment_false() {
+    let source = r#"
+        let a = if 4 == 3 {
+            1; 2; 3; 4;
+            panic()
+        } else {
+            1; 2; 3; 4;
+            42
+        };
+        a"#;
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(22, 24)
+                ),
+                (Instruction::jump(6, true), Span(27, 28)),
+                (Instruction::load_constant(0, 2, false), Span(41, 42)),
+                (Instruction::load_constant(1, 3, false), Span(44, 45)),
+                (Instruction::load_constant(2, 1, false), Span(47, 48)),
+                (Instruction::load_constant(3, 0, false), Span(50, 51)),
+                (
+                    Instruction::call_native(4, NativeFunction::Panic, 0),
+                    Span(65, 72)
+                ),
+                (Instruction::jump(5, true), Span(138, 139)),
+                (Instruction::load_constant(5, 2, false), Span(102, 103)),
+                (Instruction::load_constant(6, 3, false), Span(105, 106)),
+                (Instruction::load_constant(7, 1, false), Span(108, 109)),
+                (Instruction::load_constant(8, 0, false), Span(111, 112)),
+                (Instruction::load_constant(9, 4, false), Span(126, 128)),
+                (Instruction::r#move(9, 4), Span(138, 139)),
+                (Instruction::define_local(9, 0, false), Span(13, 14)),
+                (Instruction::get_local(10, 0), Span(148, 149)),
+                (Instruction::r#return(true), Span(149, 149)),
+            ],
+            vec![
+                Value::integer(4),
+                Value::integer(3),
+                Value::integer(1),
+                Value::integer(2),
+                Value::integer(42),
+                Value::string("a")
+            ],
+            vec![Local::new(5, None, false, Scope::default(), 0)]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(42))));
+}
+
+#[test]
+fn if_else_assigment_true() {
+    let source = r#"
+        let a = if 4 == 4 {
+            1; 2; 3; 4;
+            42
+        } else {
+            1; 2; 3; 4;
+            panic()
+        };
+        a"#;
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 0)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(22, 24)
+                ),
+                (Instruction::jump(6, true), Span(27, 28)),
+                (Instruction::load_constant(0, 1, false), Span(41, 42)),
+                (Instruction::load_constant(1, 2, false), Span(44, 45)),
+                (Instruction::load_constant(2, 3, false), Span(47, 48)),
+                (Instruction::load_constant(3, 0, false), Span(50, 51)),
+                (Instruction::load_constant(4, 4, false), Span(65, 67)),
+                (Instruction::jump(5, true), Span(138, 139)),
+                (Instruction::load_constant(5, 1, false), Span(97, 98)),
+                (Instruction::load_constant(6, 2, false), Span(100, 101)),
+                (Instruction::load_constant(7, 3, false), Span(103, 104)),
+                (Instruction::load_constant(8, 0, false), Span(106, 107)),
+                (
+                    Instruction::call_native(9, NativeFunction::Panic, 0),
+                    Span(121, 128)
+                ),
+                (Instruction::r#move(9, 4), Span(138, 139)),
+                (Instruction::define_local(9, 0, false), Span(13, 14)),
+                (Instruction::get_local(10, 0), Span(148, 149)),
+                (Instruction::r#return(true), Span(149, 149)),
+            ],
+            vec![
+                Value::integer(4),
+                Value::integer(1),
+                Value::integer(2),
+                Value::integer(3),
+                Value::integer(42),
+                Value::string("a")
+            ],
+            vec![Local::new(5, None, false, Scope::default(), 0)]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(42))));
+}
+
+#[test]
+fn if_else_complex() {
+    let source = "
+        if 1 == 1 {
+            1; 2; 3; 4;
+        } else {
+            1; 2; 3; 4;
+        }";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 0)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(14, 16)
+                ),
+                (Instruction::jump(5, true), Span(19, 20)),
+                (Instruction::load_constant(0, 0, false), Span(33, 34)),
+                (Instruction::load_constant(1, 1, false), Span(36, 37)),
+                (Instruction::load_constant(2, 2, false), Span(39, 40)),
+                (Instruction::load_constant(3, 3, false), Span(42, 43)),
+                (Instruction::jump(4, true), Span(95, 95)),
+                (Instruction::load_constant(4, 0, false), Span(74, 75)),
+                (Instruction::load_constant(5, 1, false), Span(77, 78)),
+                (Instruction::load_constant(6, 2, false), Span(80, 81)),
+                (Instruction::load_constant(7, 3, false), Span(83, 84)),
+                (Instruction::r#move(7, 3), Span(95, 95)),
+                (Instruction::r#return(false), Span(95, 95)),
+            ],
+            vec![
+                Value::integer(1),
+                Value::integer(2),
+                Value::integer(3),
+                Value::integer(4),
+            ],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(None));
+}
+
+// #[test]
+// fn if_else_nested() {
+//     let source = r#"
+//         if 0 == 1 {
+//             if 0 == 2 {
+//                 1;
+//             } else {
+//                 2;
+//             }
+//         } else {
+//             if 0 == 3 {
+//                 3;
+//             } else {
+//                 4;
+//             }
+//         }"#;
+
+//     assert_eq!(
+//         parse(source),
+//         Ok(Chunk::with_data(
+//             None,
+//             vec![
+//                 (
+//                     *Instruction::equal(true, 0, 1)
+//                         .set_b_is_constant()
+//                         .set_c_is_constant(),
+//                     Span(14, 16)
+//                 ),
+//                 (Instruction::jump(7, true), Span(14, 16)),
+//                 (
+//                     *Instruction::equal(true, 0, 2)
+//                         .set_b_is_constant()
+//                         .set_c_is_constant(),
+//                     Span(38, 41)
+//                 ),
+//                 (Instruction::jump(3, true), Span(38, 41)),
+//                 (Instruction::load_constant(0, 1, false), Span(61, 62)),
+//                 (Instruction::jump(1, true1), Span(95, 95)),
+//                 (
+//                     *Instruction::equal(true, 0, 3)
+//                         .set_b_is_constant()
+//                         .set_c_is_constant(),
+//                     Span(77, 79)
+//                 ),
+//                 (Instruction::jump(3, true), Span(77, 79)),
+//                 (Instruction::load_constant(0, 2, false), Span(94, 95)),
+//                 (Instruction::jump(1, true1), Span(95, 95)),
+//                 (Instruction::load_constant(0, 3, false), Span(114, 115)),
+//                 (Instruction::jump(1, true1), Span(95, 95)),
+//                 (Instruction::load_constant(0, 4, false), Span(134, 135)),
+//                 (Instruction::r#return(true), Span(146, 146)),
+//             ],
+//             vec![
+//                 Value::integer(0),
+//                 Value::integer(1),
+//                 Value::integer(0),
+//                 Value::integer(2),
+//                 Value::integer(1),
+//                 Value::integer(0),
+//                 Value::integer(3),
+//                 Value::integer(3),
+//                 Value::integer(4)
+//             ],
+//             vec![]
+//         ))
+//     );
+
+//     assert_eq!(run(source), Ok(Some(Value::integer(4))));
+// }
+
+#[test]
+fn if_else_false() {
+    let source = "if 1 == 2 { panic() } else { 42 }";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(5, 7)
+                ),
+                (Instruction::jump(1, true), Span(10, 11)),
+                (
+                    Instruction::call_native(0, NativeFunction::Panic, 0),
+                    Span(12, 19)
+                ),
+                (Instruction::load_constant(1, 2, true), Span(29, 31)),
+                (Instruction::r#move(1, 0), Span(33, 33)),
+                (Instruction::r#return(true), Span(33, 33)),
+            ],
+            vec![Value::integer(1), Value::integer(2), Value::integer(42)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(42))));
+}
+
+#[test]
+fn if_else_true() {
+    let source = "if 1 == 1 { 42 } else { panic() }";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 0)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(5, 7)
+                ),
+                (Instruction::jump(1, true), Span(10, 11)),
+                (Instruction::load_constant(0, 1, true), Span(12, 14)),
+                (
+                    Instruction::call_native(1, NativeFunction::Panic, 0),
+                    Span(24, 31)
+                ),
+                (Instruction::r#move(1, 0), Span(33, 33)),
+                (Instruction::r#return(true), Span(33, 33))
+            ],
+            vec![Value::integer(1), Value::integer(42)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(42))));
+}
+
+#[test]
+fn if_false() {
+    let source = "if 1 == 2 { 2 }";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(5, 7)
+                ),
+                (Instruction::jump(1, true), Span(10, 11)),
+                (Instruction::load_constant(0, 1, false), Span(12, 13)),
+                (Instruction::r#return(false), Span(15, 15))
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(None));
+}
+
+#[test]
+fn if_true() {
+    let source = "if 1 == 1 { 2 }";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::equal(true, 0, 0)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(5, 7)
+                ),
+                (Instruction::jump(1, true), Span(10, 11)),
+                (Instruction::load_constant(0, 1, false), Span(12, 13)),
+                (Instruction::r#return(false), Span(15, 15))
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(None));
+}
--- a/dust-lang/tests/functions.rs
+++ b/dust-lang/tests/functions.rs
@ -0,0 +1,126 @@
+use dust_lang::*;
+
+#[test]
+fn function() {
+    let source = "fn(a: int, b: int) -> int { a + b }";
+
+    assert_eq!(
+        run(source),
+        Ok(Some(Value::function(
+            Chunk::with_data(
+                None,
+                vec![
+                    (Instruction::add(2, 0, 1), Span(30, 31)),
+                    (Instruction::r#return(true), Span(35, 35)),
+                ],
+                vec![Value::string("a"), Value::string("b"),],
+                vec![
+                    Local::new(0, Some(Type::Integer), false, Scope::default(), 0),
+                    Local::new(1, Some(Type::Integer), false, Scope::default(), 1)
+                ]
+            ),
+            FunctionType {
+                type_parameters: None,
+                value_parameters: Some(vec![(0, Type::Integer), (1, Type::Integer)]),
+                return_type: Some(Box::new(Type::Integer)),
+            }
+        )))
+    );
+}
+
+#[test]
+fn function_call() {
+    let source = "fn(a: int, b: int) -> int { a + b }(1, 2)";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(0, 36)),
+                (Instruction::load_constant(1, 1, false), Span(36, 37)),
+                (Instruction::load_constant(2, 2, false), Span(39, 40)),
+                (Instruction::call(3, 0, 2), Span(35, 41)),
+                (Instruction::r#return(true), Span(41, 41)),
+            ],
+            vec![
+                Value::function(
+                    Chunk::with_data(
+                        None,
+                        vec![
+                            (Instruction::add(2, 0, 1), Span(30, 31)),
+                            (Instruction::r#return(true), Span(35, 36)),
+                        ],
+                        vec![Value::string("a"), Value::string("b"),],
+                        vec![
+                            Local::new(0, Some(Type::Integer), false, Scope::default(), 0),
+                            Local::new(1, Some(Type::Integer), false, Scope::default(), 1)
+                        ]
+                    ),
+                    FunctionType {
+                        type_parameters: None,
+                        value_parameters: Some(vec![(0, Type::Integer), (1, Type::Integer)]),
+                        return_type: Some(Box::new(Type::Integer)),
+                    }
+                ),
+                Value::integer(1),
+                Value::integer(2)
+            ],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(3))));
+}
+
+#[test]
+fn function_declaration() {
+    let source = "fn add (a: int, b: int) -> int { a + b }";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 1, false), Span(0, 40)),
+                (Instruction::define_local(0, 0, false), Span(3, 6)),
+                (Instruction::r#return(false), Span(40, 40))
+            ],
+            vec![
+                Value::string("add"),
+                Value::function(
+                    Chunk::with_data(
+                        None,
+                        vec![
+                            (Instruction::add(2, 0, 1), Span(35, 36)),
+                            (Instruction::r#return(true), Span(40, 40)),
+                        ],
+                        vec![Value::string("a"), Value::string("b")],
+                        vec![
+                            Local::new(0, Some(Type::Integer), false, Scope::default(), 0),
+                            Local::new(1, Some(Type::Integer), false, Scope::default(), 1)
+                        ]
+                    ),
+                    FunctionType {
+                        type_parameters: None,
+                        value_parameters: Some(vec![(0, Type::Integer), (1, Type::Integer)]),
+                        return_type: Some(Box::new(Type::Integer)),
+                    },
+                )
+            ],
+            vec![Local::new(
+                0,
+                Some(Type::Function(FunctionType {
+                    type_parameters: None,
+                    value_parameters: Some(vec![(0, Type::Integer), (1, Type::Integer)]),
+                    return_type: Some(Box::new(Type::Integer)),
+                })),
+                false,
+                Scope::default(),
+                0
+            ),],
+        )),
+    );
+
+    assert_eq!(run(source), Ok(None));
+}
--- a/dust-lang/tests/lists.rs
+++ b/dust-lang/tests/lists.rs
@ -0,0 +1,127 @@
+use dust_lang::*;
+
+#[test]
+fn empty_list() {
+    let source = "[]";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_list(0, 0), Span(0, 2)),
+                (Instruction::r#return(true), Span(2, 2)),
+            ],
+            vec![],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::abstract_list(0, 0, Type::Any))));
+}
+
+#[test]
+fn list() {
+    let source = "[1, 2, 3]";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(1, 2)),
+                (Instruction::load_constant(1, 1, false), Span(4, 5)),
+                (Instruction::load_constant(2, 2, false), Span(7, 8)),
+                (Instruction::load_list(3, 0), Span(0, 9)),
+                (Instruction::r#return(true), Span(9, 9)),
+            ],
+            vec![Value::integer(1), Value::integer(2), Value::integer(3)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(
+        run(source),
+        Ok(Some(Value::abstract_list(0, 3, Type::Integer)))
+    );
+}
+
+#[test]
+fn list_with_complex_expression() {
+    let source = "[1, 2 + 3 - 4 * 5]";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(1, 2)),
+                (
+                    *Instruction::add(1, 1, 2)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(6, 7)
+                ),
+                (
+                    *Instruction::multiply(2, 3, 4)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(14, 15)
+                ),
+                (Instruction::subtract(3, 1, 2), Span(10, 11)),
+                (Instruction::close(1, 3), Span(17, 18)),
+                (Instruction::load_list(4, 0), Span(0, 18)),
+                (Instruction::r#return(true), Span(18, 18)),
+            ],
+            vec![
+                Value::integer(1),
+                Value::integer(2),
+                Value::integer(3),
+                Value::integer(4),
+                Value::integer(5)
+            ],
+            vec![]
+        )),
+    );
+
+    assert_eq!(
+        run(source),
+        Ok(Some(Value::abstract_list(0, 4, Type::Integer)))
+    );
+}
+
+#[test]
+fn list_with_simple_expression() {
+    let source = "[1, 2 + 3, 4]";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(1, 2)),
+                (
+                    *Instruction::add(1, 1, 2)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(6, 7)
+                ),
+                (Instruction::load_constant(2, 3, false), Span(11, 12)),
+                (Instruction::load_list(3, 0), Span(0, 13)),
+                (Instruction::r#return(true), Span(13, 13)),
+            ],
+            vec![
+                Value::integer(1),
+                Value::integer(2),
+                Value::integer(3),
+                Value::integer(4),
+            ],
+            vec![]
+        )),
+    );
+
+    assert_eq!(
+        run(source),
+        Ok(Some(Value::abstract_list(0, 3, Type::Integer)))
+    );
+}
--- a/dust-lang/tests/logic.rs
+++ b/dust-lang/tests/logic.rs
@ -0,0 +1,77 @@
+use dust_lang::*;
+
+#[test]
+fn and() {
+    let source = "true && false";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_boolean(0, true, false), Span(0, 4)),
+                (Instruction::test(0, false), Span(5, 7)),
+                (Instruction::jump(1, true), Span(5, 7)),
+                (Instruction::load_boolean(1, false, false), Span(8, 13)),
+                (Instruction::r#return(true), Span(13, 13)),
+            ],
+            vec![],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(false))));
+}
+
+#[test]
+fn or() {
+    let source = "true || false";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_boolean(0, true, false), Span(0, 4)),
+                (Instruction::test(0, true), Span(5, 7)),
+                (Instruction::jump(1, true), Span(5, 7)),
+                (Instruction::load_boolean(1, false, false), Span(8, 13)),
+                (Instruction::r#return(true), Span(13, 13)),
+            ],
+            vec![],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(true))));
+}
+
+#[test]
+fn variable_and() {
+    let source = "let a = true; let b = false; a && b";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_boolean(0, true, false), Span(8, 12)),
+                (Instruction::define_local(0, 0, false), Span(4, 5)),
+                (Instruction::load_boolean(1, false, false), Span(22, 27)),
+                (Instruction::define_local(1, 1, false), Span(18, 19)),
+                (Instruction::get_local(2, 0), Span(29, 30)),
+                (Instruction::test(2, false), Span(31, 33)),
+                (Instruction::jump(1, true), Span(31, 33)),
+                (Instruction::get_local(3, 1), Span(34, 35)),
+                (Instruction::r#return(true), Span(35, 35)),
+            ],
+            vec![Value::string("a"), Value::string("b"),],
+            vec![
+                Local::new(0, None, false, Scope::default(), 0),
+                Local::new(1, None, false, Scope::default(), 1),
+            ]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(false))));
+}
--- a/dust-lang/tests/loops.rs
+++ b/dust-lang/tests/loops.rs
@ -0,0 +1,35 @@
+use dust_lang::*;
+
+#[test]
+fn r#while() {
+    let source = "let mut x = 0; while x < 5 { x = x + 1 } x";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(12, 13)),
+                (Instruction::define_local(0, 0, true), Span(8, 9)),
+                (
+                    *Instruction::less(true, 0, 2).set_c_is_constant(),
+                    Span(23, 24)
+                ),
+                (Instruction::jump(2, true), Span(41, 42)),
+                (*Instruction::add(0, 0, 3).set_c_is_constant(), Span(39, 40)),
+                (Instruction::jump(3, false), Span(41, 42)),
+                (Instruction::get_local(1, 0), Span(41, 42)),
+                (Instruction::r#return(true), Span(42, 42)),
+            ],
+            vec![
+                Value::integer(0),
+                Value::string("x"),
+                Value::integer(5),
+                Value::integer(1),
+            ],
+            vec![Local::new(1, None, true, Scope::default(), 0),]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(5))));
+}
--- a/dust-lang/tests/math.rs
+++ b/dust-lang/tests/math.rs
@ -0,0 +1,324 @@
+use dust_lang::*;
+
+#[test]
+fn add() {
+    let source = "1 + 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::add(0, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 3)
+                ),
+                (Instruction::r#return(true), Span(5, 5))
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(3))));
+}
+
+#[test]
+fn add_assign() {
+    let source = "let mut a = 1; a += 2; a";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(12, 13)),
+                (Instruction::define_local(0, 0, true), Span(8, 9)),
+                (*Instruction::add(0, 0, 2).set_c_is_constant(), Span(17, 19)),
+                (Instruction::get_local(1, 0), Span(23, 24)),
+                (Instruction::r#return(true), Span(24, 24))
+            ],
+            vec![Value::integer(1), Value::string("a"), Value::integer(2)],
+            vec![Local::new(1, None, true, Scope::default(), 0)]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(3))));
+}
+
+#[test]
+fn add_assign_expects_mutable_variable() {
+    let source = "1 += 2";
+
+    assert_eq!(
+        compile(source),
+        Err(DustError::Compile {
+            error: CompileError::ExpectedMutableVariable {
+                found: Token::Integer("1").to_owned(),
+                position: Span(0, 1)
+            },
+            source
+        })
+    );
+}
+
+// #[test]
+// fn add_expects_integer_float_or_string() {
+//     let source = "true + false";
+
+//     assert_eq!(
+//         parse(source),
+//         Err(DustError::Parse {
+//             error: ParseError::ExpectedIntegerFloatOrString {
+//                 found: Token::True,
+//                 position: Span(0, 3)
+//             },
+//             source
+//         })
+//     );
+// }
+
+#[test]
+fn divide() {
+    let source = "2 / 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::divide(0, 0, 0)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 3)
+                ),
+                (Instruction::r#return(true), Span(5, 5))
+            ],
+            vec![Value::integer(2)],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(1))));
+}
+
+#[test]
+fn divide_assign() {
+    let source = "let mut a = 2; a /= 2; a";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(12, 13)),
+                (Instruction::define_local(0, 0, true), Span(8, 9)),
+                (
+                    *Instruction::divide(0, 0, 0).set_c_is_constant(),
+                    Span(17, 19)
+                ),
+                (Instruction::get_local(1, 0), Span(23, 24)),
+                (Instruction::r#return(true), Span(24, 24))
+            ],
+            vec![Value::integer(2), Value::string("a")],
+            vec![Local::new(1, None, true, Scope::default(), 0)]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(1))));
+}
+
+#[test]
+fn divide_assign_expects_mutable_variable() {
+    let source = "1 -= 2";
+
+    assert_eq!(
+        compile(source),
+        Err(DustError::Compile {
+            error: CompileError::ExpectedMutableVariable {
+                found: Token::Integer("1").to_owned(),
+                position: Span(0, 1)
+            },
+            source
+        })
+    );
+}
+
+#[test]
+fn math_operator_precedence() {
+    let source = "1 + 2 - 3 * 4 / 5";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::add(0, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 3)
+                ),
+                (
+                    *Instruction::multiply(1, 2, 3)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(10, 11)
+                ),
+                (
+                    *Instruction::divide(2, 1, 4).set_c_is_constant(),
+                    Span(14, 15)
+                ),
+                (Instruction::subtract(3, 0, 2), Span(6, 7)),
+                (Instruction::r#return(true), Span(17, 17)),
+            ],
+            vec![
+                Value::integer(1),
+                Value::integer(2),
+                Value::integer(3),
+                Value::integer(4),
+                Value::integer(5),
+            ],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(1))));
+}
+
+#[test]
+fn multiply() {
+    let source = "1 * 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::multiply(0, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 3)
+                ),
+                (Instruction::r#return(true), Span(5, 5)),
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(2))));
+}
+
+#[test]
+fn multiply_assign() {
+    let source = "let mut a = 2; a *= 3 a";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(12, 13)),
+                (Instruction::define_local(0, 0, true), Span(8, 9)),
+                (
+                    *Instruction::multiply(0, 0, 2).set_c_is_constant(),
+                    Span(17, 19)
+                ),
+                (Instruction::get_local(1, 0), Span(22, 23)),
+                (Instruction::r#return(true), Span(23, 23))
+            ],
+            vec![Value::integer(2), Value::string("a"), Value::integer(3)],
+            vec![Local::new(1, None, true, Scope::default(), 0),]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(6))));
+}
+
+#[test]
+fn multiply_assign_expects_mutable_variable() {
+    let source = "1 *= 2";
+
+    assert_eq!(
+        compile(source),
+        Err(DustError::Compile {
+            error: CompileError::ExpectedMutableVariable {
+                found: Token::Integer("1").to_owned(),
+                position: Span(0, 1)
+            },
+            source
+        })
+    );
+}
+
+#[test]
+fn subtract() {
+    let source = "1 - 2";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (
+                    *Instruction::subtract(0, 0, 1)
+                        .set_b_is_constant()
+                        .set_c_is_constant(),
+                    Span(2, 3)
+                ),
+                (Instruction::r#return(true), Span(5, 5)),
+            ],
+            vec![Value::integer(1), Value::integer(2)],
+            vec![]
+        ))
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(-1))));
+}
+
+#[test]
+fn subtract_assign() {
+    let source = "let mut x = 42; x -= 2; x";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(12, 14)),
+                (Instruction::define_local(0, 0, true), Span(8, 9)),
+                (
+                    *Instruction::subtract(0, 0, 2).set_c_is_constant(),
+                    Span(18, 20)
+                ),
+                (Instruction::get_local(1, 0), Span(24, 25)),
+                (Instruction::r#return(true), Span(25, 25)),
+            ],
+            vec![Value::integer(42), Value::string("x"), Value::integer(2)],
+            vec![Local::new(1, None, true, Scope::default(), 0)]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(40))));
+}
+
+#[test]
+fn subtract_assign_expects_mutable_variable() {
+    let source = "1 -= 2";
+
+    assert_eq!(
+        compile(source),
+        Err(DustError::Compile {
+            error: CompileError::ExpectedMutableVariable {
+                found: Token::Integer("1").to_owned(),
+                position: Span(0, 1)
+            },
+            source
+        })
+    );
+}
--- a/dust-lang/tests/native_functions.rs
+++ b/dust-lang/tests/native_functions.rs
@ -0,0 +1,59 @@
+use dust_lang::*;
+
+#[test]
+fn panic() {
+    let source = "panic(\"Goodbye world!\", 42)";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(6, 22)),
+                (Instruction::load_constant(1, 1, false), Span(24, 26)),
+                (
+                    Instruction::call_native(2, NativeFunction::Panic, 2),
+                    Span(0, 27)
+                ),
+                (Instruction::r#return(true), Span(27, 27))
+            ],
+            vec![Value::string("Goodbye world!"), Value::integer(42)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(
+        run(source),
+        Err(DustError::Runtime {
+            error: VmError::NativeFunction(NativeFunctionError::Panic {
+                message: Some("Goodbye world! 42".to_string()),
+                position: Span(0, 27)
+            }),
+            source
+        })
+    )
+}
+
+#[test]
+fn to_string() {
+    let source = "to_string(42)";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(10, 12)),
+                (
+                    Instruction::call_native(1, NativeFunction::ToString, 1),
+                    Span(0, 13)
+                ),
+                (Instruction::r#return(true), Span(13, 13))
+            ],
+            vec![Value::integer(42)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::string("42"))))
+}
--- a/dust-lang/tests/scopes.rs
+++ b/dust-lang/tests/scopes.rs
@ -1,47 +1,244 @@
 use dust_lang::*;

 #[test]
-fn block_scope_captures_parent() {
-    let source = "let x = 42; { x }";
+fn allow_access_to_parent_scope() {
+    let source = r#"
+        let x = 1;
+        {
+            x
+        }
+    "#;

-    assert_eq!(run(source), Ok(Some(Value::integer(42))));
+    assert_eq!(run(source), Ok(Some(Value::integer(1))));
 }

 #[test]
-fn block_scope_does_not_capture_child() {
-    env_logger::builder().is_test(true).try_init().unwrap();
+fn block_scope() {
+    let source = "
+        let a = 0;
+        {
+            let b = 42;
+            {
+                let c = 1;
+            }
+            let d = 2;
+        }
+        let e = 1;
+    ";

-    let source = "{ let x = 42; } x";
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(17, 18)),
+                (Instruction::define_local(0, 0, false), Span(13, 14)),
+                (Instruction::load_constant(1, 2, false), Span(50, 52)),
+                (Instruction::define_local(1, 1, false), Span(46, 47)),
+                (Instruction::load_constant(2, 4, false), Span(92, 93)),
+                (Instruction::define_local(2, 2, false), Span(88, 89)),
+                (Instruction::load_constant(3, 6, false), Span(129, 130)),
+                (Instruction::define_local(3, 3, false), Span(125, 126)),
+                (Instruction::load_constant(4, 4, false), Span(158, 159)),
+                (Instruction::define_local(4, 4, false), Span(154, 155)),
+                (Instruction::r#return(false), Span(165, 165))
+            ],
+            vec![
+                Value::integer(0),
+                Value::string("a"),
+                Value::integer(42),
+                Value::string("b"),
+                Value::integer(1),
+                Value::string("c"),
+                Value::integer(2),
+                Value::string("d"),
+                Value::string("e"),
+            ],
+            vec![
+                Local::new(1, None, false, Scope::new(0, 0), 0),
+                Local::new(3, None, false, Scope::new(1, 1), 1),
+                Local::new(5, None, false, Scope::new(2, 2), 2),
+                Local::new(7, None, false, Scope::new(1, 1), 3),
+                Local::new(8, None, false, Scope::new(0, 0), 4),
+            ]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(None));
+}
+
+#[test]
+fn multiple_block_scopes() {
+    let source = "
+        let a = 0;
+        {
+            let b = 42;
+            {
+                let c = 1;
+            }
+            let d = 2;
+        }
+        let q = 42;
+        {
+            let b = 42;
+            {
+                let c = 1;
+            }
+            let d = 2;
+        }
+        let e = 1;
+    ";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(17, 18)),
+                (Instruction::define_local(0, 0, false), Span(13, 14)),
+                (Instruction::load_constant(1, 2, false), Span(50, 52)),
+                (Instruction::define_local(1, 1, false), Span(46, 47)),
+                (Instruction::load_constant(2, 4, false), Span(92, 93)),
+                (Instruction::define_local(2, 2, false), Span(88, 89)),
+                (Instruction::load_constant(3, 6, false), Span(129, 130)),
+                (Instruction::define_local(3, 3, false), Span(125, 126)),
+                (Instruction::load_constant(4, 2, false), Span(158, 160)),
+                (Instruction::define_local(4, 4, false), Span(154, 155)),
+                (Instruction::load_constant(5, 2, false), Span(192, 194)),
+                (Instruction::define_local(5, 5, false), Span(188, 189)),
+                (Instruction::load_constant(6, 4, false), Span(234, 235)),
+                (Instruction::define_local(6, 6, false), Span(230, 231)),
+                (Instruction::load_constant(7, 6, false), Span(271, 272)),
+                (Instruction::define_local(7, 7, false), Span(267, 268)),
+                (Instruction::load_constant(8, 4, false), Span(300, 301)),
+                (Instruction::define_local(8, 8, false), Span(296, 297)),
+                (Instruction::r#return(false), Span(307, 307))
+            ],
+            vec![
+                Value::integer(0),
+                Value::string("a"),
+                Value::integer(42),
+                Value::string("b"),
+                Value::integer(1),
+                Value::string("c"),
+                Value::integer(2),
+                Value::string("d"),
+                Value::string("q"),
+                Value::string("e"),
+            ],
+            vec![
+                Local::new(1, None, false, Scope::new(0, 0), 0),
+                Local::new(3, None, false, Scope::new(1, 1), 1),
+                Local::new(5, None, false, Scope::new(2, 2), 2),
+                Local::new(7, None, false, Scope::new(1, 1), 3),
+                Local::new(8, None, false, Scope::new(0, 0), 4),
+                Local::new(3, None, false, Scope::new(1, 3), 5),
+                Local::new(5, None, false, Scope::new(2, 4), 6),
+                Local::new(7, None, false, Scope::new(1, 3), 7),
+                Local::new(9, None, false, Scope::new(0, 0), 8),
+            ]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(None));
+}
+
+#[test]
+fn disallow_access_to_child_scope() {
+    let source = r#"
+        {
+            let x = 1;
+        }
+        x
+    "#;

    assert_eq!(
        run(source),
-        Err(DustError::analysis(
-            [AnalysisError::UndefinedVariable {
-                identifier: Node::new(Identifier::new("x"), (16, 17))
-            }],
+        Err(DustError::Compile {
+            error: CompileError::VariableOutOfScope {
+                identifier: "x".to_string(),
+                position: Span(52, 53),
+                variable_scope: Scope::new(1, 1),
+                access_scope: Scope::new(0, 0),
+            },
            source
-        ))
+        })
    );
 }

 #[test]
-fn block_scope_does_not_capture_sibling() {
-    let source = "{ let x = 42; } { x }";
+fn disallow_access_to_child_scope_nested() {
+    let source = r#"
+        {
+            {
+                let x = 1;
+            }
+            x
+        }
+    "#;

    assert_eq!(
        run(source),
-        Err(DustError::analysis(
-            [AnalysisError::UndefinedVariable {
-                identifier: Node::new(Identifier::new("x"), (18, 19))
-            }],
+        Err(DustError::Compile {
+            error: CompileError::VariableOutOfScope {
+                identifier: "x".to_string(),
+                position: Span(78, 79),
+                variable_scope: Scope::new(2, 2),
+                access_scope: Scope::new(1, 1),
+            },
            source
-        ))
+        })
    );
 }

 #[test]
-fn block_scope_does_not_pollute_parent() {
-    let source = "let x = 42; { let x = \"foo\"; let x = \"bar\"; } x";
+fn disallow_access_to_sibling_scope() {
+    let source = r#"
+        {
+            let x = 1;
+        }
+        {
+            x
+        }
+    "#;

-    assert_eq!(run(source), Ok(Some(Value::integer(42))));
+    assert_eq!(
+        run(source),
+        Err(DustError::Compile {
+            error: CompileError::VariableOutOfScope {
+                identifier: "x".to_string(),
+                variable_scope: Scope::new(1, 1),
+                access_scope: Scope::new(1, 2),
+                position: Span(66, 67),
+            },
+            source
+        })
+    );
+}
+
+#[test]
+fn disallow_access_to_sibling_scope_nested() {
+    let source = r#"
+        {
+            {
+                let x = 1;
+            }
+            {
+                x
+            }
+        }
+    "#;
+
+    assert_eq!(
+        run(source),
+        Err(DustError::Compile {
+            error: CompileError::VariableOutOfScope {
+                identifier: "x".to_string(),
+                variable_scope: Scope::new(2, 2),
+                access_scope: Scope::new(2, 3),
+                position: Span(96, 97),
+            },
+            source
+        })
+    );
 }
--- a/dust-lang/tests/unary_operations.rs
+++ b/dust-lang/tests/unary_operations.rs
@ -0,0 +1,42 @@
+use dust_lang::*;
+
+#[test]
+fn negate() {
+    let source = "-(42)";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (*Instruction::negate(0, 0).set_b_is_constant(), Span(0, 1)),
+                (Instruction::r#return(true), Span(5, 5)),
+            ],
+            vec![Value::integer(42)],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(-42))));
+}
+
+#[test]
+fn not() {
+    let source = "!true";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_boolean(0, true, false), Span(1, 5)),
+                (Instruction::not(1, 0), Span(0, 1)),
+                (Instruction::r#return(true), Span(5, 5)),
+            ],
+            vec![],
+            vec![]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::boolean(false))));
+}
--- a/dust-lang/tests/variables.rs
+++ b/dust-lang/tests/variables.rs
@ -0,0 +1,63 @@
+use dust_lang::*;
+
+#[test]
+fn define_local() {
+    let source = "let x = 42;";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(8, 10)),
+                (Instruction::define_local(0, 0, false), Span(4, 5)),
+                (Instruction::r#return(false), Span(11, 11))
+            ],
+            vec![Value::integer(42), Value::string("x")],
+            vec![Local::new(1, None, false, Scope::default(), 0)]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(None));
+}
+
+#[test]
+fn let_statement_expects_identifier() {
+    let source = "let 1 = 2";
+
+    assert_eq!(
+        compile(source),
+        Err(DustError::Compile {
+            error: CompileError::ExpectedToken {
+                expected: TokenKind::Identifier,
+                found: Token::Integer("1").to_owned(),
+                position: Span(4, 5)
+            },
+            source
+        })
+    );
+}
+
+#[test]
+fn set_local() {
+    let source = "let mut x = 41; x = 42; x";
+
+    assert_eq!(
+        compile(source),
+        Ok(Chunk::with_data(
+            None,
+            vec![
+                (Instruction::load_constant(0, 0, false), Span(12, 14)),
+                (Instruction::define_local(0, 0, true), Span(8, 9)),
+                (Instruction::load_constant(1, 2, false), Span(20, 22)),
+                (Instruction::set_local(1, 0), Span(16, 17)),
+                (Instruction::get_local(2, 0), Span(24, 25)),
+                (Instruction::r#return(true), Span(25, 25)),
+            ],
+            vec![Value::integer(41), Value::string("x"), Value::integer(42)],
+            vec![Local::new(1, None, true, Scope::default(), 0)]
+        )),
+    );
+
+    assert_eq!(run(source), Ok(Some(Value::integer(42))));
+}
--- a/dust-shell/Cargo.toml
+++ b/dust-shell/Cargo.toml
@ -9,5 +9,7 @@ repository.workspace = true

 [dependencies]
 clap = { version = "4.5.14", features = ["derive"] }
+colored = "2.1.0"
 dust-lang = { path = "../dust-lang" }
 env_logger = "0.11.5"
+log = "0.4.22"
--- a/dust-shell/src/main.rs
+++ b/dust-shell/src/main.rs
@ -1,55 +1,138 @@
-use std::fs::read_to_string;
+use std::{fs::read_to_string, io::Write};

 use clap::Parser;
-use dust_lang::run;
+use colored::Colorize;
+use dust_lang::{compile, format, run};
+use log::{Level, LevelFilter};

 #[derive(Parser)]
 struct Cli {
+    /// Source code sent via command line
    #[arg(short, long)]
    command: Option<String>,

+    /// Whether to output formatted source code
+    #[arg(short, long)]
+    format: bool,
+
+    /// Whether to output line numbers in formatted source code
+    #[arg(long)]
+    format_line_numbers: Option<bool>,
+
+    /// Whether to output colors in formatted source code
+    #[arg(long)]
+    format_colored: Option<bool>,
+
+    /// Whether to output the disassembled chunk
    #[arg(short, long)]
    parse: bool,

+    /// Whether to style the disassembled chunk
+    #[arg(long)]
+    style_disassembly: Option<bool>,
+
+    /// Log level
+    #[arg(short, long)]
+    log: Option<LevelFilter>,
+
+    /// Path to a source code file
    path: Option<String>,
 }

 fn main() {
-    env_logger::init();
-
    let args = Cli::parse();
+    let mut logger = env_logger::builder();

-    if let Some(command) = &args.command {
-        if args.parse {
-            parse_and_display_errors(command);
+    logger.format(|buf, record| {
+        let level_display = match record.level() {
+            Level::Info => "INFO".bold().white(),
+            Level::Debug => "DEBUG".bold().blue(),
+            Level::Warn => "WARN".bold().yellow(),
+            Level::Error => "ERROR".bold().red(),
+            Level::Trace => "TRACE".bold().purple(),
+        };
+        let module = record
+            .module_path()
+            .map(|path| path.split("::").last().unwrap_or(path))
+            .unwrap_or("unknown")
+            .dimmed();
+        let display = format!("{level_display:5} {module:^6} {args}", args = record.args());
+
+        writeln!(buf, "{display}")
+    });
+
+    if let Some(level) = args.log {
+        logger.filter_level(level).init();
    } else {
-            run_and_display_errors(command);
+        logger.parse_env("DUST_LOG").init();
+    }
+
+    let source = if let Some(path) = &args.path {
+        &read_to_string(path).expect("Failed to read file")
+    } else if let Some(command) = &args.command {
+        command
+    } else {
+        eprintln!("No input provided");
+
+        return;
+    };
+
+    if args.format {
+        let line_numbers = args.format_line_numbers.unwrap_or(true);
+        let colored = args.format_colored.unwrap_or(true);
+
+        log::info!("Formatting source");
+
+        match format(source, line_numbers, colored) {
+            Ok(formatted) => println!("{}", formatted),
+            Err(error) => {
+                eprintln!("{}", error.report());
+            }
+        }
    }
-    } else if let Some(path) = &args.path {
-        let source = read_to_string(path).expect("Failed to read file");

    if args.parse {
-            parse_and_display_errors(&source);
-        } else {
-            run_and_display_errors(&source);
-        }
-    }
-}
+        let styled = args.style_disassembly.unwrap_or(true);

-fn parse_and_display_errors(source: &str) {
-    match dust_lang::parse(source) {
-        Ok(ast) => println!("{:#?}", ast),
-        Err(error) => eprintln!("{}", error.report()),
-    }
-}
+        log::info!("Parsing source");
+
+        match compile(source) {
+            Ok(chunk) => {
+                let disassembly = chunk
+                    .disassembler()
+                    .source(source)
+                    .styled(styled)
+                    .disassemble();
+
+                println!("{}", disassembly);
+            }
+            Err(error) => {
+                eprintln!("{}", error.report());
+            }
+        }
+    }
+
+    if args.format || args.parse {
+        return;
+    }

-fn run_and_display_errors(source: &str) {
    match run(source) {
-        Ok(return_value) => {
-            if let Some(value) = return_value {
-                println!("{}", value);
+        Ok(Some(value)) => println!("{}", value),
+        Ok(None) => {}
+        Err(error) => {
+            eprintln!("{}", error.report());
        }
    }
-        Err(error) => eprintln!("{}", error.report()),
-    }
+}
+
+#[cfg(test)]
+mod tests {
+    use clap::CommandFactory;
+
+    use super::*;
+
+    #[test]
+    fn verify_cli() {
+        Cli::command().debug_assert();
+    }
 }
--- a/examples/assets/count.js
+++ b/examples/assets/count.js
@ -0,0 +1,5 @@
+var i = 0;
+
+while (i < 10000) {
+  i++;
+}
--- a/examples/assets/fibonacci.js
+++ b/examples/assets/fibonacci.js
@ -0,0 +1,11 @@
+function fib(n) {
+  if (n <= 0) {
+    return 0;
+  } else if (n === 1) {
+    return 1;
+  } else {
+    return fib(n - 1) + fib(n - 2);
+  }
+}
+
+console.log(fib(25));
--- a/examples/count.ds
+++ b/examples/count.ds
@ -0,0 +1,5 @@
+let mut i = 0;
+
+while i < 10000 {
+    i += 1;
+}
--- a/examples/fibonacci.ds
+++ b/examples/fibonacci.ds
@ -0,0 +1,8 @@
+fn fib (n: int) -> int {
+    if n <= 0 { return 0 }
+    if n == 1 { return 1 }
+
+    fib(n - 1) + fib(n - 2)
+}
+
+write_line(fib(25))
--- a/examples/fizzbuzz.ds
+++ b/examples/fizzbuzz.ds
@ -11,7 +11,7 @@ while count <= 15 {
 	} else if divides_by_5 {
 		"buzz"
 	} else {
-		count.to_string()
+		to_string(count)
 	}

 	write_line(output)
Author	SHA1	Message	Date
Jeff	bb345a7938	Fix argument retrieval in native functions	2024-11-07 03:05:32 -05:00
Jeff	04a1c81a2a	Add parents to the VM; Improve the disassembler	2024-11-07 02:10:02 -05:00
Jeff	f54d2d0d22	Clean up	2024-11-07 00:49:36 -05:00
Jeff	3a6c05a79c	Begin rewriting the README	2024-11-06 19:18:38 -05:00
Jeff	ea88ffc451	Move the disassembler to its own module	2024-11-06 18:39:09 -05:00
Jeff	a997665d1a	Write docs; Improve disassembly output	2024-11-06 17:59:16 -05:00
Jeff	dc9b451b37	Clean up and add docs	2024-11-06 15:50:05 -05:00
Jeff	e99a7b5e1e	Rename Parser to Compiler	2024-11-06 15:40:37 -05:00
Jeff	74bb8a429a	Clean up	2024-11-06 15:14:12 -05:00
Jeff	d587d87ed7	Refine chunk poisoning and optimize taking values from registers	2024-11-06 15:08:51 -05:00
Jeff	87f597624a	Begin fixing control flow	2024-11-06 14:46:23 -05:00
Jeff	78840cf3e7	Bring back chunk errors	2024-11-06 13:50:49 -05:00
Jeff	c0b998c0d8	Add optimizer	2024-11-06 13:09:29 -05:00
Jeff	e2df823566	Clean up value methods	2024-11-06 03:54:58 -05:00
Jeff	f08c7c6f1f	Refine values to be either abstract or concrete	2024-11-06 03:36:46 -05:00
Jeff	a16f7795de	Continue addind type evaluation	2024-11-06 00:57:54 -05:00
Jeff	314913dbf5	Begin adding type evaluation to the parser	2024-11-05 23:20:58 -05:00
Jeff	9294b8f7ed	Use macro to simplify operation code	2024-11-05 22:28:10 -05:00
Jeff	ea46bfe5da	Simplify the parser by removing a value	2024-11-05 22:10:13 -05:00
Jeff	9650183c73	Replace some "if let" statements with "matches!" macro for better formatting	2024-11-05 22:07:54 -05:00
Jeff	3330939128	Add docs	2024-11-05 19:38:26 -05:00
Jeff	dd13d2efee	Clean up main.rs	2024-11-05 17:39:04 -05:00
Jeff	b0af1609f0	Improve chunk disassembly code	2024-11-05 17:35:54 -05:00
Jeff	80b6380255	Clean up	2024-11-05 16:33:56 -05:00
Jeff	5ff5568e95	Clean up	2024-11-05 16:25:55 -05:00
Jeff	cfb4fa66b5	Fix scopes	2024-11-05 16:07:51 -05:00
Jeff	8c72e921dc	Rework how scopes work to support excluding sibling scopes	2024-11-05 12:44:16 -05:00
Jeff	0dcfcd5375	Clean up	2024-11-04 21:32:00 -05:00
Jeff	a2fa5afcd4	Clean up	2024-11-04 21:30:23 -05:00
Jeff	c77e1c89a9	Update dependencies and allow compiling to wasm	2024-11-04 21:29:20 -05:00
Jeff	34dca01d85	Modicy native functions to have a full type specification	2024-11-04 19:16:19 -05:00
Jeff	0e7aae79f9	Change identifiers to be constant values	2024-11-04 18:07:58 -05:00
Jeff	a2e7a4e73e	Begin removing chunk errors; Use constants for identifiers	2024-11-04 15:38:58 -05:00
Jeff	a9e675cb4f	Clean up native functions	2024-11-04 09:34:26 -05:00
Jeff	60535e20d6	Deduplication of constants in the chunk; Clean up	2024-11-04 08:08:56 -05:00
Jeff	e85297bcbb	Extend macro use in native functions	2024-11-03 01:30:41 -05:00
Jeff	1947d66be5	Overhaul implicit returns and add lots of new native functions	2024-11-02 21:24:41 -04:00
Jeff	ae6d3d7a82	Add new implicit return for end of file	2024-11-01 09:55:15 -04:00
Jeff	7e4f6654a4	Add move instruction to fix assignment to conditionals	2024-11-01 02:51:18 -04:00
Jeff	32ff52d9b3	Change binary argument handling to fix expression chaining	2024-10-31 21:40:42 -04:00
Jeff	febd7bb054	Fix while loop jumps; Pass tests	2024-10-31 20:33:46 -04:00
Jeff	604962c535	Begin refactoring jump instructions	2024-10-30 14:48:30 -04:00
Jeff	1f9adfab2f	Fix test	2024-10-30 10:30:56 -04:00
Jeff	10abd91c85	Add failing control flow test with new panic function	2024-10-30 09:50:45 -04:00
Jeff	bd23853657	Add native function errors	2024-10-30 09:32:46 -04:00
Jeff	382d43ef77	Add NativeFunction macro and implement read_line	2024-10-30 09:11:28 -04:00
Jeff	4d6412006a	Add lots of new native functions	2024-10-30 08:02:22 -04:00
Jeff	d7be203bfc	Fix write and write_line	2024-10-30 05:31:46 -04:00
Jeff	c264aaeb13	Add the to_string, write and write_line natives	2024-10-30 05:16:34 -04:00
Jeff	af4e43fc9f	Add native calls and the panic native	2024-10-30 03:08:25 -04:00
Jeff	caf1c22af0	Clean up	2024-10-30 00:16:10 -04:00
Jeff	e304195661	Change return to use last_assigned_value; Add scopes tests	2024-10-29 23:11:55 -04:00
Jeff	004cf73959	Pass tests	2024-10-24 22:37:18 -04:00
Jeff	c0f74f1e09	Tweak control flow jumping and compile-time optimizations	2024-10-20 22:18:58 -04:00
Jeff	648bbdbc4d	Refactor parsing for better jumping and returns	2024-10-20 18:51:04 -04:00
Jeff	1da61f0873	Begin reworking jump instructions	2024-10-20 10:20:09 -04:00
Jeff	8db37bcdfd	Add LoadSelf instruction to enable recursion	2024-10-20 02:30:22 -04:00
Jeff	6caae6c952	Add chunk names	2024-10-20 00:46:59 -04:00
Jeff	f15cf84c4d	Refactor to fix bugs with loops; Add close instructions while calling functions	2024-10-20 00:06:22 -04:00
Jeff	13b4cfffcc	Add function declarations to the parser	2024-10-19 19:13:19 -04:00
Jeff	9d5c9d9fd0	Implement functions calls	2024-10-19 17:24:22 -04:00
Jeff	65e513488f	Clean up unused code	2024-10-19 13:52:23 -04:00
Jeff	1c8e8b35b9	Remove old, unused code from the parser	2024-10-19 13:40:46 -04:00
Jeff	3f8b554a86	Refactor parser and chunk to have fewer errors and less retrospection	2024-10-19 12:05:20 -04:00
Jeff	8c79157fa7	Simplify and clean up	2024-10-19 03:06:14 -04:00
Jeff	6bcc5b1555	Add function test	2024-10-19 01:58:30 -04:00
Jeff	b7153df9be	Pass tests	2024-10-19 01:04:53 -04:00
Jeff	bfade78a0d	Consume VM and chunk when running the VM	2024-10-18 23:34:48 -04:00
Jeff	8b70a1dcc4	Clean up	2024-10-18 23:09:07 -04:00
Jeff	589e59b8c4	Clean up	2024-10-18 23:03:50 -04:00
Jeff	86e055a562	Clean up	2024-10-18 22:30:20 -04:00
Jeff	19f2d19134	Clean up	2024-10-18 21:34:47 -04:00
Jeff	95e5b3062d	Fix lexing bug	2024-10-18 19:31:46 -04:00
Jeff	44659ec34a	Extend CLI to cover more formatting options; Extend formatting	2024-10-13 16:46:45 -04:00
Jeff	0c758c9768	Clean up	2024-10-13 13:08:12 -04:00
Jeff	12d34d6354	Add a new parser method to handle errors	2024-10-13 13:01:58 -04:00
Jeff	3609fddaea	Expand formatter	2024-10-13 12:04:32 -04:00
Jeff	5d62d897f4	Ads no-run command to the CLI	2024-10-13 08:04:32 -04:00
Jeff	565d3c54f1	Add format option to the CLI	2024-10-13 07:56:11 -04:00
Jeff	02ee7d126c	Clean up	2024-10-13 07:45:16 -04:00
Jeff	c7bba88875	Create formatter	2024-10-13 07:14:12 -04:00
Jeff	5eb901f468	Add a VM method; Refactor and clean up	2024-10-13 04:21:07 -04:00
Jeff	055f0a4100	Continue working on function calls	2024-10-13 02:47:12 -04:00
Jeff	d5fc68e466	Refactor chunk disassembly output	2024-10-13 02:33:58 -04:00
Jeff	743679371d	Fix function bug	2024-10-12 20:34:13 -04:00
Jeff	2864bee057	Add types to functions and improve calls	2024-10-12 20:19:21 -04:00
Jeff	2527cc2de7	Clean up	2024-10-12 10:57:22 -04:00
Jeff	ea0be43199	Begin adding function calls	2024-10-12 10:55:34 -04:00
Jeff	5bbda1a24e	Disallow comparison chaining	2024-10-12 08:16:06 -04:00
Jeff	f1034534ed	Avoid emitting duplicate return instructions; Clean up	2024-10-12 07:12:44 -04:00
Jeff	02877d06d3	Reduce use of TokenKind in parser to only error cases	2024-10-12 06:27:19 -04:00
Jeff	30b2801a38	Add item type to list value; Clean up	2024-10-12 06:17:16 -04:00
Jeff	9c612317dc	Refactor values to use register pointers for complex values	2024-10-12 04:50:30 -04:00
Jeff	6e1ef77192	Refactor to use index references to avoid cloning values	2024-10-12 03:06:44 -04:00
Jeff	c1e372d7cf	Improve disassembler output; Fix return positions	2024-10-09 19:59:06 -04:00
Jeff	61d633392c	Improve disassembler output	2024-10-09 17:34:11 -04:00
Jeff	b6c3b1e5ba	Refactor	2024-10-09 12:16:46 -04:00
Jeff	259721f6cb	Continue implemnting functions; Begin adding types	2024-10-09 06:15:06 -04:00
Jeff	bdc34cb10e	Begin adding functions to the language	2024-10-08 22:56:01 -04:00
Jeff	dddbf77fac	Fix bug in the VM	2024-10-05 21:30:48 -04:00
Jeff	79cc59c952	Make minor changes to fizzbuzz example	2024-10-05 06:42:19 -04:00
Jeff	35f73d60f0	Add tests for parser errors	2024-10-05 05:57:28 -04:00
Jeff	437a6bf164	Add math-assignment operators	2024-10-05 04:33:38 -04:00
Jeff	d857f42434	Pass all tests	2024-10-05 02:07:26 -04:00
Jeff	9d0aa13e8a	Refactor VM, chunk and parser to pass tests	2024-10-05 00:11:03 -04:00
Jeff	9b1dc6c55c	Rewrite tests for consistency	2024-10-04 22:36:33 -04:00
Jeff	5015cf4cc4	Refactor how return instruction works; Begin passing tests	2024-10-04 22:33:47 -04:00
Jeff	5411a1db27	Move and replace lots of tests; Refactor parser	2024-10-04 22:21:17 -04:00
Jeff	ba904fdcd8	Clean up disassembler output	2024-10-01 20:27:28 -04:00
Jeff	9d1996c9ec	Simplify parsing comparison expressions	2024-10-01 20:07:57 -04:00
Jeff	88684f49b6	Small refactor to jump position	2024-09-27 13:16:41 -04:00
Jeff	d0d80cf407	Use test for single registers in conditional expressions	2024-09-25 09:55:10 -04:00
Jeff	47d6ea417d	Improve logs; Clean up	2024-09-25 01:27:10 -04:00
Jeff	daca836db1	Refine LoadList instruction; Improve logs; Refactor	2024-09-24 22:58:14 -04:00
Jeff	60df8b4d64	Remove identiifer cache and extend some tests	2024-09-24 20:32:52 -04:00
Jeff	95e22aa97f	Pass tests	2024-09-24 17:49:30 -04:00
Jeff	7afde989f9	Fix bugs in binary parsing and running	2024-09-24 16:49:17 -04:00
Jeff	85241c04b9	Fix lists	2024-09-24 13:51:04 -04:00
Jeff	c1eccf049f	Add list test	2024-09-24 12:03:12 -04:00
Jeff	855782c370	Pass tests	2024-09-24 11:40:12 -04:00
Jeff	a6da34a79c	Fix control flow	2024-09-24 10:16:19 -04:00
Jeff	3df42f6a47	Refine equality implementation	2024-09-24 08:29:33 -04:00
Jeff	1d03876b89	Write tests	2024-09-24 01:30:21 -04:00
Jeff	5441938725	Add better parser error	2024-09-24 00:24:09 -04:00
Jeff	c31991cc24	Fix and pass tests	2024-09-23 23:38:49 -04:00
Jeff	9fe3e440ac	Add and pass tests	2024-09-23 19:16:15 -04:00
Jeff	182ef66f23	Refactor register incrementing/decrementing	2024-09-23 11:15:49 -04:00
Jeff	d68c789ea8	Add test for equality chain	2024-09-23 08:57:49 -04:00
Jeff	1d0bafa4a3	Refine binary parsing	2024-09-23 06:42:41 -04:00
Jeff	2c485cf046	Implement logical and/or operators	2024-09-23 04:01:36 -04:00
Jeff	c5c2fe95ae	Implement unary operators and divide binary parsing	2024-09-23 01:45:52 -04:00
Jeff	23f733d8b2	Extend parsing	2024-09-23 00:55:39 -04:00
Jeff	57edf48e36	Extend parsing	2024-09-22 18:17:21 -04:00
Jeff	573e5ae470	Change VM's final value to last modified register	2024-09-22 12:57:58 -04:00
Jeff	31bb7eaffc	Pass tests	2024-09-19 18:07:11 -04:00
Jeff	d4a8a65096	Pass tests	2024-09-19 13:54:28 -04:00
Jeff	dee09d3583	Add bytcode to dissassembly	2024-09-19 11:53:41 -04:00
Jeff	be77d64c39	Pass all but one test	2024-09-19 11:41:18 -04:00
Jeff	03113fdf5e	Clean up	2024-09-18 23:02:28 -04:00
Jeff	bf4f319302	Add and pass tests	2024-09-18 22:00:24 -04:00
Jeff	a1dd7e3bb9	Add if/else test	2024-09-18 20:08:02 -04:00
Jeff	5b3232c723	Refactor and clean up; Pass tests	2024-09-18 20:02:12 -04:00
Jeff	413cb70731	Begin implementing control flow with if/else expressions	2024-09-18 16:43:34 -04:00
Jeff	915340fbdb	Add LoadBoolean; Refactor; Improve disassembly output	2024-09-18 13:42:32 -04:00
Jeff	85b95a56aa	Add mutable variables	2024-09-18 11:27:41 -04:00
Jeff	2cb03297c5	Add test	2024-09-18 08:33:29 -04:00
Jeff	56f1222cfc	Fix block test	2024-09-18 08:29:00 -04:00
Jeff	89573e81b9	Fix bugs in binary parsing	2024-09-18 08:24:57 -04:00
Jeff	fa4c2d48a3	Implement better closing for blocks	2024-09-18 07:58:31 -04:00
Jeff	0a16c5e0ca	Fix binary expressions with variables	2024-09-18 01:21:40 -04:00
Jeff	2f8c46f0a5	Implement closing for lists	2024-09-17 23:06:58 -04:00
Jeff	37dc2e05c5	Clean up	2024-09-17 21:10:44 -04:00
Jeff	f02c3d1fb5	Add lists	2024-09-17 19:35:33 -04:00
Jeff	6ca96bc1dc	Add &&, \|\| and ! to the language; Add tests	2024-09-17 17:51:39 -04:00
Jeff	00555785e3	Refactor pratt parsing	2024-09-17 17:23:37 -04:00
Jeff	6c76006ad9	Improve test	2024-09-17 13:39:12 -04:00
Jeff	0d55bb7244	Fix binary expression parsing	2024-09-17 13:24:45 -04:00
Jeff	fd4ffeec7c	Pass tests	2024-09-17 12:08:40 -04:00
Jeff	71a4f863e3	Add test	2024-09-15 10:20:43 -04:00
Jeff	9cb6873618	Add test	2024-09-15 06:33:56 -04:00
Jeff	b66710e3eb	Improve precedence parsing	2024-09-15 06:26:31 -04:00
Jeff	4653a3f506	Improve on proof of concept	2024-09-15 04:25:24 -04:00
Jeff	97bde437e8	Pass tests and fix instruction byte encoding bug	2024-09-15 02:03:54 -04:00
Jeff	d1bdabed56	Continue register proof of concept	2024-09-15 01:24:04 -04:00
Jeff	ba80774e7b	Refactor and debug	2024-09-14 21:05:03 -04:00
Jeff	aa8b1215a8	Clean up	2024-09-14 15:06:13 -04:00
Jeff	9418cd5b70	Add "styled" CLI option and debug logging for disassembler	2024-09-14 14:31:40 -04:00
Jeff	8534f18c9a	Tweak the chunk disassembly	2024-09-14 13:59:11 -04:00
Jeff	2ad3440097	Clean up	2024-09-13 02:30:09 -04:00
Jeff	3b7987c218	Replace local variables with indexes to the register	2024-09-13 02:28:18 -04:00
Jeff	a0439675b7	Fix bugs and improve disassembler	2024-09-13 01:10:07 -04:00
Jeff	82a2b8f6b7	Fix byte lexing bug; Implement Move operation	2024-09-12 21:14:15 -04:00
Jeff	5c54a5b9bd	Make chunk disassembly the prettiest thing ever	2024-09-12 19:25:20 -04:00
Jeff	9144257524	Replace VM's "clone" method with "take" to avoid cloning values	2024-09-12 14:22:07 -04:00
Jeff	caf59894b6	Fix and implement variable getting and setting	2024-09-12 14:16:26 -04:00
Jeff	8b33df3d4a	Prettify the hell out of chunk disassembly	2024-09-12 13:03:24 -04:00
Jeff	78c9ed97e2	Experiment with instruction optimization	2024-09-12 09:11:49 -04:00
Jeff	6ff25a22ec	Fix lexing bug that I just created	2024-09-12 05:12:38 -04:00
Jeff	d4d58e793b	Refactor and improve the VM, Parser, and Lexer	2024-09-12 05:08:55 -04:00
Jeff	67e5de6664	Reimplement the Parser and VM with a register-based VM	2024-09-12 00:39:31 -04:00
Jeff	7b055d79b5	Begin rewrite with register-based bytecode	2024-09-11 23:07:20 -04:00
Jeff	974310ffab	Preffify logs	2024-09-11 04:33:53 -04:00
Jeff	86f8e47b0c	Avoid cloning constant and move identifier stack to the chunk	2024-09-11 04:22:54 -04:00
Jeff	e4204c1b0d	Get variable scopes working	2024-09-11 03:10:12 -04:00
Jeff	8f58bf30a4	Make everything messy	2024-09-10 18:19:59 -04:00
Jeff	c3790e90bf	Implement blocks with scopes	2024-09-10 10:44:15 -04:00
Jeff	4ba3a47ae5	Add implicit returns and fix variable declaration and resolution	2024-09-10 09:26:05 -04:00
Jeff	f936c30b4f	Go to great lengths to avoid cloning Values; Extend error reports	2024-09-10 03:42:25 -04:00
Jeff	0ed2733991	Add quotes to string value display	2024-09-10 01:06:38 -04:00
Jeff	8798efc0af	Add error reports and byte operations	2024-09-10 01:04:30 -04:00
Jeff	8f20e53880	Add support for characters and bytes	2024-09-09 23:45:35 -04:00
Jeff	fcfcb4a429	Restructure, clean up and add tests	2024-09-09 23:24:22 -04:00
Jeff	85f5f44946	Pass all tests	2024-09-09 22:57:14 -04:00
Jeff	5b8ec74d05	Prettify disassembly output	2024-09-09 20:55:00 -04:00
Jeff	c406039c99	Replace global variables with locals	2024-09-09 19:23:49 -04:00
Jeff	32347ec512	Make chunk debug print infallible	2024-09-07 18:48:01 -04:00
Jeff	e9ec838b25	Refactor and clean up	2024-09-07 17:16:14 -04:00
Jeff	b8957190e0	Add and pass tests	2024-09-07 13:51:05 -04:00
Jeff	3ac15fe70b	Implement let assignment	2024-09-07 12:15:47 -04:00
Jeff	03d44434e2	Refactor parsing	2024-09-07 06:38:12 -04:00
Jeff	616f890028	Pass parser test	2024-09-07 04:37:38 -04:00
Jeff	812d930488	Continue writing bytecode implementation	2024-09-07 04:34:03 -04:00
Jeff	406edda573	Begin parser	2024-09-06 23:30:43 -04:00
Jeff	3c2e3699ab	Add binary operations	2024-09-06 19:37:12 -04:00
Jeff	1ecaac0819	Start new rewrite of Dust	2024-09-06 19:27:16 -04:00