Continue new VM implementation; Write docs

Cargo.lock

@@ -102,15 +102,6 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
-[[package]]
-name = "bitflags"
-version = "2.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
-dependencies = [
- "serde",
-]
-
 [[package]]
 name = "bumpalo"
 version = "3.16.0"
@@ -141,7 +132,7 @@ version = "2.34.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a0610544180c38b88101fecf2dd634b174a62eef6946f84dfc6a7127512b381c"
 dependencies = [
- "bitflags 1.3.2",
+ "bitflags",
  "textwrap",
  "unicode-width",
 ]
@@ -314,7 +305,6 @@ name = "dust-lang"
 version = "0.5.0"
 dependencies = [
  "annotate-snippets",
- "bitflags 2.6.0",
  "colored",
  "criterion",
  "getrandom",

dust-cli/src/main.rs

@@ -4,9 +4,11 @@ use std::{fs::read_to_string, path::PathBuf};
 
 use clap::{Args, Parser};
 use colored::Colorize;
-use dust_lang::{compile, CompileError, Compiler, DustError, Lexer, Span, Token, Vm};
+use dust_lang::{compile, CompileError, Compiler, DustError, DustString, Lexer, Span, Token, Vm};
 use log::{Level, LevelFilter};
 
+const DEFAULT_PROGRAM_NAME: &str = "Dust CLI Input";
+
 #[derive(Parser)]
 #[clap(
     name = env!("CARGO_PKG_NAME"),
@@ -196,7 +198,7 @@ fn main() {
         }
     }
 
-    let chunk = compiler.finish();
+    let chunk = compiler.finish(Some(DEFAULT_PROGRAM_NAME));
     let compile_end = start_time.elapsed();
 
     let vm = Vm::new(chunk);

dust-lang/Cargo.toml

@@ -22,7 +22,6 @@ smallvec = { version = "1.13.2", features = ["const_generics", "serde"] }
 smartstring = { version = "1.0.1", features = [
     "serde",
 ], default-features = false }
-bitflags = { version = "2.6.0", features = ["serde"] }
 
 [dev-dependencies]
 criterion = { version = "0.3.4", features = ["html_reports"] }

dust-lang/src/chunk/disassembler.rs

@@ -263,7 +263,7 @@ impl<'a, W: Write> Disassembler<'a, W> {
             self.write_char(border[1])?;
         }
 
-        self.write_char(border[2]);
+        self.write_char(border[2])?;
         self.write_char('\n')
     }
 
@@ -377,7 +377,7 @@ impl<'a, W: Write> Disassembler<'a, W> {
     }
 
     pub fn write_prototype_section(&mut self) -> Result<(), io::Error> {
-        self.write_center_border_bold("Functions");
+        self.write_center_border_bold("Functions")?;
 
         for chunk in &self.chunk.prototypes {
             chunk

dust-lang/src/chunk/mod.rs

@@ -27,7 +27,8 @@ use std::io::Write;
 use serde::{Deserialize, Serialize};
 use smallvec::SmallVec;
 
-use crate::{DustString, FunctionType, Instruction, Span, Value};
+use crate::vm::{Record, Register, RunAction};
+use crate::{DustString, Function, FunctionType, Instruction, Span, Value};
 
 /// Representation of a Dust program or function.
 ///
@@ -44,6 +45,7 @@ pub struct Chunk {
     prototypes: Vec<Chunk>,
 
     stack_size: usize,
+    record_index: u8,
 }
 
 impl Chunk {
@@ -56,6 +58,7 @@ impl Chunk {
         locals: impl Into<SmallVec<[Local; 8]>>,
         prototypes: impl Into<Vec<Chunk>>,
         stack_size: usize,
+        record_index: u8,
     ) -> Self {
         Self {
             name,
@@ -66,6 +69,7 @@ impl Chunk {
             locals: locals.into(),
             prototypes: prototypes.into(),
             stack_size,
+            record_index,
         }
     }
 
@@ -88,31 +92,47 @@ impl Chunk {
             locals: locals.into(),
             prototypes,
             stack_size: 0,
+            record_index: 0,
         }
     }
 
-    pub fn take_data(
+    pub fn as_function(&self) -> Function {
-        self,
+        Function {
-    ) -> (
+            name: self.name.clone(),
-        Option<DustString>,
+            r#type: self.r#type.clone(),
-        FunctionType,
+            record_index: self.record_index,
-        SmallVec<[Instruction; 32]>,
+        }
-        SmallVec<[Span; 32]>,
+    }
-        SmallVec<[Value; 16]>,
+
-        SmallVec<[Local; 8]>,
+    pub fn into_records(self, records: &mut Vec<Record>) {
-        Vec<Chunk>,
+        let actions = self.instructions().iter().map(RunAction::from).collect();
-        usize,
+        let record = Record::new(
-    ) {
+            actions,
-        (
+            None,
             self.name,
             self.r#type,
-            self.instructions,
             self.positions,
             self.constants,
             self.locals,
-            self.prototypes,
             self.stack_size,
-        )
+            self.record_index,
+        );
+
+        if records.is_empty() {
+            records.push(record);
+
+            for chunk in self.prototypes {
+                chunk.into_records(records);
+            }
+        } else {
+            for chunk in self.prototypes {
+                chunk.into_records(records);
+            }
+
+            debug_assert!(record.index() as usize == records.len());
+
+            records.push(record);
+        }
     }
 
     pub fn name(&self) -> Option<&DustString> {

dust-lang/src/compiler/error.rs

@@ -20,7 +20,7 @@ pub enum CompileError {
     },
 
     // Parsing errors
-    CannotChainComparison {
+    ComparisonChain {
         position: Span,
     },
     ExpectedBoolean {
@@ -176,7 +176,7 @@ impl AnnotatedError for CompileError {
         match self {
             Self::CannotAddArguments { .. } => "Cannot add these types",
             Self::CannotAddType { .. } => "Cannot add to this type",
-            Self::CannotChainComparison { .. } => "Cannot chain comparison operations",
+            Self::ComparisonChain { .. } => "Cannot chain comparison operations",
             Self::CannotDivideArguments { .. } => "Cannot divide these types",
             Self::CannotDivideType { .. } => "Cannot divide this type",
             Self::CannotModuloArguments { .. } => "Cannot modulo these types",

dust-lang/src/compiler/mod.rs

@@ -1,9 +1,12 @@
-//! Compilation tools and errors
+//! The Dust compiler and its accessories.
 //!
 //! This module provides two compilation options:
-//! - [`compile`] borrows a string and returns a chunk, handling the entire compilation process and
+//! - [`compile`] is a simple function that borrows a string and returns a chunk, handling
-//!   turning any resulting [`ComplileError`] into a [`DustError`].
+//!   compilation and turning any resulting error into a [`DustError`], which can easily display a
-//! - [`Compiler`] uses a lexer to get tokens and assembles a chunk.
+//!   detailed report. The main chunk will be named "main".
+//! - [`Compiler`] is created with a [`Lexer`] and protentially emits a [`CompileError`] or
+//!   [`LexError`] if the input is invalid. Allows passing a name for the main chunk when
+//!   [`Compiler::finish`] is called.
 mod error;
 mod optimize;
 
@@ -15,12 +18,12 @@ use std::{
 };
 
 use colored::Colorize;
-use optimize::{optimize_test_with_explicit_booleans, optimize_test_with_loader_arguments};
+use optimize::control_flow_register_consolidation;
 use smallvec::{smallvec, SmallVec};
 
 use crate::{
     instruction::{
-        CallNative, Close, GetLocal, Jump, LoadList, Negate, Not, Point, Return, SetLocal, Test,
+        CallNative, Close, GetLocal, Jump, LoadList, Negate, Not, Return, SetLocal, Test,
     },
     Argument, Chunk, ConcreteValue, DustError, DustString, FunctionType, Instruction, Lexer, Local,
     NativeFunction, Operation, Scope, Span, Token, TokenKind, Type, Value,
@@ -35,7 +38,7 @@ use crate::{
 /// let source = "40 + 2 == 42";
 /// let chunk = compile(source).unwrap();
 ///
-/// assert_eq!(chunk.len(), 3);
+/// assert_eq!(chunk.instructions().len(), 3);
 /// ```
 pub fn compile(source: &str) -> Result<Chunk, DustError> {
     let lexer = Lexer::new(source);
@@ -45,12 +48,14 @@ pub fn compile(source: &str) -> Result<Chunk, DustError> {
         .compile()
         .map_err(|error| DustError::compile(error, source))?;
 
-    let chunk = compiler.finish();
+    let name = DustString::from("main");
+    let chunk = compiler.finish(Some(name));
 
     Ok(chunk)
 }
 
-/// Tool for compiling the input a token at a time while assembling a chunk.
+/// The Dust compiler assembles a [`Chunk`] for the Dust VM. Any unrecognized symbols, disallowed
+/// syntax or conflicting type usage will result in an error.
 ///
 /// See the [`compile`] function an example of how to create and use a Compiler.
 #[derive(Debug)]
@@ -58,9 +63,10 @@ pub struct Compiler<'src> {
     /// Used to get tokens for the compiler.
     lexer: Lexer<'src>,
 
-    /// Name of the function or program being compiled. This is assigned to the chunk when
+    /// Name of the function being compiled. This is used to identify recursive calls, so it should
-    /// [`Compiler::finish`] is called.
+    /// be `None` for the main chunk. The main chunk can still be named by passing a name to
-    self_name: Option<DustString>,
+    /// [`Compiler::finish`], which will override this value.
+    function_name: Option<DustString>,
 
     /// Type of the function being compiled. This is assigned to the chunk when [`Compiler::finish`]
     /// is called.
@@ -116,6 +122,7 @@ pub struct Compiler<'src> {
 }
 
 impl<'src> Compiler<'src> {
+    /// Creates a new compiler with the given lexer.
     pub fn new(mut lexer: Lexer<'src>) -> Result<Self, CompileError> {
         let (current_token, current_position) = lexer.next_token()?;
 
@@ -126,7 +133,7 @@ impl<'src> Compiler<'src> {
         );
 
         Ok(Compiler {
-            self_name: None,
+            function_name: None,
             r#type: FunctionType {
                 type_parameters: None,
                 value_parameters: None,
@@ -150,7 +157,12 @@ impl<'src> Compiler<'src> {
         })
     }
 
-    pub fn finish(self) -> Chunk {
+    /// Creates a new chunk with the compiled data, optionally assigning a name to the chunk.
+    ///
+    /// Note for maintainers: Do not give a name when compiling functions, only the main chunk. This
+    /// will allow [`Compiler::function_name`] to be both the name used for recursive calls and the
+    /// name of the function when it is compiled. The name can later be seen in the VM's call stack.
+    pub fn finish(self, name: Option<impl Into<DustString>>) -> Chunk {
         log::info!("End chunk");
 
         let (instructions, positions): (SmallVec<[Instruction; 32]>, SmallVec<[Span; 32]>) = self
@@ -163,9 +175,12 @@ impl<'src> Compiler<'src> {
             .into_iter()
             .map(|(local, _)| local)
             .collect::<SmallVec<[Local; 8]>>();
+        let chunk_name = name
+            .map(|into_name| into_name.into())
+            .or(self.function_name);
 
         Chunk::new(
-            self.self_name,
+            chunk_name,
             self.r#type,
             instructions,
             positions,
@@ -173,9 +188,13 @@ impl<'src> Compiler<'src> {
             locals,
             self.prototypes,
             self.stack_size,
+            self.record_index,
         )
     }
 
+    /// Compiles the source while checking for errors and returning a [`CompileError`] if any are
+    /// found. After calling this function, check its return value for an error, then call
+    /// [`Compiler::finish`] to get the compiled chunk.
     pub fn compile(&mut self) -> Result<(), CompileError> {
         loop {
             self.parse(Precedence::None)?;
@@ -852,7 +871,7 @@ impl<'src> Compiler<'src> {
         if let Some([Operation::EQUAL | Operation::LESS | Operation::LESS_EQUAL, _, _]) =
             self.get_last_operations()
         {
-            return Err(CompileError::CannotChainComparison {
+            return Err(CompileError::ComparisonChain {
                 position: self.current_position,
             });
         }
@@ -915,13 +934,13 @@ impl<'src> Compiler<'src> {
             }
         };
         let jump = Instruction::jump(1, true);
-        let load_false = Instruction::load_boolean(destination, false, true);
+        let load_true = Instruction::load_boolean(destination, true, true);
-        let load_true = Instruction::load_boolean(destination, true, false);
+        let load_false = Instruction::load_boolean(destination, false, false);
 
         self.emit_instruction(comparison, Type::Boolean, operator_position);
         self.emit_instruction(jump, Type::None, operator_position);
-        self.emit_instruction(load_false, Type::Boolean, operator_position);
         self.emit_instruction(load_true, Type::Boolean, operator_position);
+        self.emit_instruction(load_false, Type::Boolean, operator_position);
 
         Ok(())
     }
@@ -932,29 +951,19 @@ impl<'src> Compiler<'src> {
             Some([Operation::TEST, Operation::JUMP, _])
         );
 
-        let (mut left_instruction, left_type, left_position) = self.pop_last_instruction()?;
+        let (left_instruction, left_type, left_position) = self.pop_last_instruction()?;
+        let (left, _) = self.handle_binary_argument(&left_instruction)?;
 
-        if is_logic_chain {
+        // if is_logic_chain {
-            let destination = self
+        //     let destination = self
-                .instructions
+        //         .instructions
-                .iter()
+        //         .iter()
-                .rev()
+        //         .rev()
-                .nth(2)
+        //         .nth(2)
-                .map_or(0, |(instruction, _, _)| instruction.a_field());
+        //         .map_or(0, |(instruction, _, _)| instruction.a_field());
 
-            left_instruction.set_a_field(destination);
+        //     left_instruction.set_a_field(destination);
-        }
+        // }
-
-        let jump_index = self.instructions.len().saturating_sub(1);
-        let mut jump_distance = if is_logic_chain {
-            self.instructions.pop().map_or(0, |(jump, _, _)| {
-                let Jump { offset, .. } = Jump::from(&jump);
-
-                offset
-            })
-        } else {
-            0
-        };
 
         if !left_instruction.yields_value() {
             return Err(CompileError::ExpectedExpression {
@@ -963,10 +972,19 @@ impl<'src> Compiler<'src> {
             });
         }
 
-        let (left, _) = self.handle_binary_argument(&left_instruction)?;
+        // self.instructions
+        //     .push((left_instruction, left_type.clone(), left_position));
 
-        self.instructions
+        // let short_circuit_jump_index = self.instructions.len();
-            .push((left_instruction, left_type.clone(), left_position));
+        // let mut short_circuit_jump_distance = if is_logic_chain {
+        //     self.instructions.pop().map_or(0, |(jump, _, _)| {
+        //         let Jump { offset, .. } = Jump::from(&jump);
+
+        //         offset
+        //     })
+        // } else {
+        //     1
+        // };
 
         let operator = self.current_token;
         let operator_position = self.current_position;
@@ -986,20 +1004,28 @@ impl<'src> Compiler<'src> {
 
         self.advance()?;
         self.emit_instruction(test, Type::None, operator_position);
-        self.emit_instruction(Instruction::jump(1, true), Type::None, operator_position);
+
+        let jump_index = self.instructions.len();
+
         self.parse_sub_expression(&rule.precedence)?;
 
+        let jump_distance = (self.instructions.len() - jump_index) as u8;
+        let jump = Instruction::jump(jump_distance, true);
+
+        self.instructions
+            .insert(jump_index, (jump, Type::None, operator_position));
+
         let (mut right_instruction, _, _) = self.instructions.last_mut().unwrap();
+
         right_instruction.set_a_field(left_instruction.a_field());
 
-        if is_logic_chain {
+        // short_circuit_jump_distance += (self.instructions.len() - short_circuit_jump_index) as u8;
-            let expression_length = self.instructions.len() - jump_index - 1;
+        // let jump = Instruction::jump(short_circuit_jump_distance, true);
-            jump_distance += expression_length as u8;
-            let jump = Instruction::jump(jump_distance, true);
 
-            self.instructions
+        // self.instructions.insert(
-                .insert(jump_index, (jump, Type::None, operator_position));
+        //     short_circuit_jump_index,
-        }
+        //     (jump, Type::None, operator_position),
+        // );
 
         Ok(())
     }
@@ -1021,7 +1047,7 @@ impl<'src> Compiler<'src> {
             local_index
         } else if let Some(native_function) = NativeFunction::from_str(identifier) {
             return self.parse_call_native(native_function);
-        } else if self.self_name.as_deref() == Some(identifier) {
+        } else if self.function_name.as_deref() == Some(identifier) {
             let destination = self.next_register();
             let load_function = Instruction::load_function(destination, self.record_index);
 
@@ -1175,35 +1201,22 @@ impl<'src> Compiler<'src> {
         self.advance()?;
         self.parse_expression()?;
 
-        if matches!(
+        let (last_instruction, _, _) = self.instructions.last().unwrap();
-            self.get_last_operations(),
+        let argument = match last_instruction.as_argument() {
-            Some([
+            Some(argument) => argument,
-                Operation::EQUAL | Operation::LESS | Operation::LESS_EQUAL,
+            None => {
-                Operation::JUMP,
+                return Err(CompileError::ExpectedExpression {
-                Operation::LOAD_BOOLEAN,
+                    found: self.previous_token.to_owned(),
-                Operation::LOAD_BOOLEAN
+                    position: self.previous_position,
-            ]),
+                });
-        ) {
+            }
-            self.instructions.pop();
+        };
-            self.instructions.pop();
+        let test = Instruction::from(Test {
-            self.instructions.pop();
+            argument,
-        } else if let Some((instruction, _, _)) = self.instructions.last() {
+            test_value: true,
-            let argument = match instruction.as_argument() {
+        });
-                Some(argument) => argument,
-                None => {
-                    return Err(CompileError::ExpectedExpression {
-                        found: self.previous_token.to_owned(),
-                        position: self.previous_position,
-                    });
-                }
-            };
-            let test = Instruction::from(Test {
-                argument,
-                test_value: true,
-            });
 
-            self.emit_instruction(test, Type::None, self.current_position)
+        self.emit_instruction(test, Type::None, self.current_position);
-        }
 
         let if_block_start = self.instructions.len();
         let if_block_start_position = self.current_position;
@@ -1211,8 +1224,8 @@ impl<'src> Compiler<'src> {
         if let Token::LeftBrace = self.current_token {
             self.parse_block()?;
         } else {
-            return Err(CompileError::ExpectedToken {
+            return Err(CompileError::ExpectedTokenMultiple {
-                expected: TokenKind::LeftBrace,
+                expected: &[TokenKind::If, TokenKind::LeftBrace],
                 found: self.current_token.to_owned(),
                 position: self.current_position,
             });
@@ -1235,15 +1248,11 @@ impl<'src> Compiler<'src> {
                     position: self.current_position,
                 });
             }
-
-            true
         } else if if_block_type != Type::None {
             return Err(CompileError::IfMissingElse {
                 position: Span(if_block_start_position.0, self.current_position.1),
             });
-        } else {
+        }
-            false
-        };
 
         let else_block_end = self.instructions.len();
         let else_block_distance = (else_block_end - if_block_end) as u8;
@@ -1288,25 +1297,18 @@ impl<'src> Compiler<'src> {
             }
         }
 
-        let jump = Instruction::from(Jump {
+        let jump = Instruction::jump(if_block_distance, true);
-            offset: if_block_distance,
-            is_positive: true,
-        });
 
         self.instructions
             .insert(if_block_start, (jump, Type::None, if_block_start_position));
 
-        optimize_test_with_explicit_booleans(self);
+        control_flow_register_consolidation(self);
-        optimize_test_with_loader_arguments(self);
 
         let else_last_register = self.next_register().saturating_sub(1);
-        let r#move = Instruction::from(Point {
+        let point = Instruction::point(else_last_register, if_last_register);
-            from: else_last_register,
-            to: if_last_register,
-        });
 
         if if_last_register < else_last_register {
-            self.emit_instruction(r#move, Type::None, self.current_position);
+            self.emit_instruction(point, else_block_type, self.current_position);
         }
 
         Ok(())
@@ -1490,9 +1492,7 @@ impl<'src> Compiler<'src> {
 
     fn parse_implicit_return(&mut self) -> Result<(), CompileError> {
         if self.allow(Token::Semicolon)? {
-            let r#return = Instruction::from(Return {
+            let r#return = Instruction::r#return(false);
-                should_return_value: false,
-            });
 
             self.emit_instruction(r#return, Type::None, self.current_position);
         } else {
@@ -1507,9 +1507,7 @@ impl<'src> Compiler<'src> {
                         }
                     });
             let should_return_value = previous_expression_type != Type::None;
-            let r#return = Instruction::from(Return {
+            let r#return = Instruction::r#return(should_return_value);
-                should_return_value,
-            });
 
             self.update_return_type(previous_expression_type.clone())?;
             self.emit_instruction(r#return, Type::None, self.current_position);
@@ -1577,7 +1575,7 @@ impl<'src> Compiler<'src> {
 
             function_compiler.advance()?;
 
-            function_compiler.self_name = Some(text.into());
+            function_compiler.function_name = Some(text.into());
 
             Some((text, position))
         } else {
@@ -1664,7 +1662,8 @@ impl<'src> Compiler<'src> {
         self.lexer.skip_to(self.current_position.1);
 
         let function_end = function_compiler.previous_position.1;
-        let chunk = function_compiler.finish();
+        let record_index = function_compiler.record_index;
+        let chunk = function_compiler.finish(None::<&str>);
         let destination = self.next_register();
 
         self.prototypes.push(chunk);
@@ -1679,7 +1678,7 @@ impl<'src> Compiler<'src> {
             );
         }
 
-        let load_function = Instruction::load_function(destination, self.record_index);
+        let load_function = Instruction::load_function(destination, record_index);
 
         self.emit_instruction(
             load_function,
@@ -1703,7 +1702,10 @@ impl<'src> Compiler<'src> {
                     position: self.previous_position,
                 })?;
 
-        if last_instruction.operation() != Operation::LOAD_FUNCTION {
+        if !matches!(
+            last_instruction_type,
+            Type::Function(_) | Type::SelfFunction
+        ) {
             return Err(CompileError::ExpectedFunction {
                 found: self.previous_token.to_owned(),
                 actual_type: last_instruction_type.clone(),
@@ -1970,29 +1972,25 @@ impl<'src> Compiler<'src> {
 /// Operator precedence levels.
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Precedence {
-    None,
+    Primary = 9,
-    Assignment,
+    Call = 8,
-    Conditional,
+    Unary = 7,
-    LogicalOr,
+    Factor = 6,
-    LogicalAnd,
+    Term = 5,
-    Equality,
+    Comparison = 4,
-    Comparison,
+    LogicalAnd = 3,
-    Term,
+    LogicalOr = 2,
-    Factor,
+    Assignment = 1,
-    Unary,
+    None = 0,
-    Call,
-    Primary,
 }
 
 impl Precedence {
     fn increment(&self) -> Self {
         match self {
             Precedence::None => Precedence::Assignment,
-            Precedence::Assignment => Precedence::Conditional,
+            Precedence::Assignment => Precedence::LogicalOr,
-            Precedence::Conditional => Precedence::LogicalOr,
             Precedence::LogicalOr => Precedence::LogicalAnd,
-            Precedence::LogicalAnd => Precedence::Equality,
+            Precedence::LogicalAnd => Precedence::Comparison,
-            Precedence::Equality => Precedence::Comparison,
             Precedence::Comparison => Precedence::Term,
             Precedence::Term => Precedence::Factor,
             Precedence::Factor => Precedence::Unary,
@@ -2036,7 +2034,7 @@ impl From<&Token<'_>> for ParseRule<'_> {
             Token::BangEqual => ParseRule {
                 prefix: None,
                 infix: Some(Compiler::parse_comparison_binary),
-                precedence: Precedence::Equality,
+                precedence: Precedence::Comparison,
             },
             Token::Bool => ParseRule {
                 prefix: Some(Compiler::expect_expression),
@@ -2082,7 +2080,7 @@ impl From<&Token<'_>> for ParseRule<'_> {
             Token::DoubleEqual => ParseRule {
                 prefix: None,
                 infix: Some(Compiler::parse_comparison_binary),
-                precedence: Precedence::Equality,
+                precedence: Precedence::Comparison,
             },
             Token::DoublePipe => ParseRule {
                 prefix: None,

dust-lang/src/compiler/optimize.rs

@@ -1,15 +1,11 @@
 //! Functions used by the compiler to optimize a chunk's bytecode during compilation.
 
-use crate::{Compiler, Operation};
+use crate::{Compiler, Instruction, Operation};
 
-/// Optimizes a control flow pattern by removing redundant instructions.
+/// Optimizes a control flow pattern to use fewer registers and avoid using a `POINT` instruction.
+/// Use this after parsing an if/else statement.
 ///
-/// If a comparison instruction is followed by a test instruction, the test instruction may be
+/// This makes the following examples compile to the same bytecode:
-/// redundant because the comparison instruction already sets the correct value. If the test's
-/// arguments (i.e. the boolean loaders) are `true` and `false` (in that order) then the boolean
-/// loaders, jump and test instructions are removed, leaving a single comparison instruction.
-///
-/// This makes the following two code snippets compile to the same bytecode:
 ///
 /// ```dust
 /// 4 == 4
@@ -19,58 +15,27 @@ use crate::{Compiler, Operation};
 /// if 4 == 4 { true } else { false }
 /// ```
 ///
-/// The instructions must be in the following order:
+/// When they occur in the sequence shown below, instructions can be optimized by taking advantage
-///     - `EQUAL`, `LESS` or `LESS_EQUAL`
+/// of the loaders' ability to skip an instruction after loading a value. If these instructions are
-///     - `TEST`
+/// the result of a binary expression, this will not change anything because they were already
-///     - `JUMP`
+/// emitted optimally. Control flow patterns, however, can be optimized because the load
-///     - `LOAD_BOOLEAN`
+/// instructions are from seperate expressions that each uses its own register. Since only one of
-///     - `LOAD_BOOLEAN`
+/// the two branches will be executed, this is wasteful. It would also require the compiler to emit
-pub fn optimize_test_with_explicit_booleans(compiler: &mut Compiler) {
+/// a `POINT` instruction to prevent the VM from encountering an empty register.
-    if matches!(
-        compiler.get_last_operations(),
-        Some([
-            Operation::EQUAL | Operation::LESS | Operation::LESS_EQUAL,
-            Operation::TEST,
-            Operation::JUMP,
-            Operation::LOAD_BOOLEAN,
-            Operation::LOAD_BOOLEAN,
-        ])
-    ) {
-        log::debug!("Removing redundant test, jump and boolean loaders after comparison");
-
-        let first_loader = compiler.instructions.iter().nth_back(1).unwrap();
-        let second_loader = compiler.instructions.last().unwrap();
-        let first_boolean = first_loader.0.b_field() != 0;
-        let second_boolean = second_loader.0.b_field() != 0;
-
-        if first_boolean && !second_boolean {
-            compiler.instructions.pop();
-            compiler.instructions.pop();
-            compiler.instructions.pop();
-            compiler.instructions.pop();
-        }
-    }
-}
-
-/// Optimizes a control flow pattern.
-///
-/// TEST instructions (which are always followed by a JUMP) can be optimized when the next
-/// instructions are two constant or boolean loaders. The first loader is set to skip an instruction
-/// if it is run while the second loader is modified to use the first's register. Foregoing the use
-/// a jump instruction is an optimization but consolidating the registers is a necessity. This is
-/// because test instructions are essentially control flow and a subsequent SET_LOCAL instruction
-/// would not know at compile time which branch would be executed at runtime.
 ///
 /// The instructions must be in the following order:
-///     - `TEST`
+///     - `EQUAL` | `LESS` | `LESS_EQUAL` | `TEST`
 ///     - `JUMP`
 ///     - `LOAD_BOOLEAN` or `LOAD_CONSTANT`
 ///     - `LOAD_BOOLEAN` or `LOAD_CONSTANT`
-pub fn optimize_test_with_loader_arguments(compiler: &mut Compiler) {
+///
+/// This optimization was taken from `A No-Frills Introduction to Lua 5.1 VM Instructions` by
+/// Kein-Hong Man.
+pub fn control_flow_register_consolidation(compiler: &mut Compiler) {
     if !matches!(
         compiler.get_last_operations(),
         Some([
-            Operation::TEST,
+            Operation::EQUAL | Operation::LESS | Operation::LESS_EQUAL | Operation::TEST,
             Operation::JUMP,
             Operation::LOAD_BOOLEAN | Operation::LOAD_CONSTANT,
             Operation::LOAD_BOOLEAN | Operation::LOAD_CONSTANT,
@@ -81,12 +46,17 @@ pub fn optimize_test_with_loader_arguments(compiler: &mut Compiler) {
 
     log::debug!("Consolidating registers for control flow optimization");
 
-    let first_loader = &mut compiler.instructions.iter_mut().nth_back(1).unwrap().0;
+    let first_loader_index = compiler.instructions.len() - 2;
-
+    let (first_loader, _, _) = &mut compiler.instructions.get_mut(first_loader_index).unwrap();
-    first_loader.set_c_field(true as u8);
-
     let first_loader_destination = first_loader.a_field();
-    let second_loader = &mut compiler.instructions.last_mut().unwrap().0;
+    *first_loader =
+        Instruction::load_boolean(first_loader.a_field(), first_loader.b_field() != 0, true);
 
-    second_loader.set_a_field(first_loader_destination);
+    let second_loader_index = compiler.instructions.len() - 1;
+    let (second_loader, _, _) = &mut compiler.instructions.get_mut(second_loader_index).unwrap();
+    *second_loader = Instruction::load_boolean(
+        first_loader_destination,
+        second_loader.b_field() != 0,
+        false,
+    );
 }

dust-lang/src/dust_error.rs

@@ -26,7 +26,20 @@ impl<'src> DustError<'src> {
     }
 
     pub fn report(&self) -> String {
-        let (title, description, detail_snippets, help_snippets) = self.error_data();
+        let (title, description, detail_snippets, help_snippets) = match self {
+            Self::Compile { error, .. } => (
+                CompileError::title(),
+                error.description(),
+                error.detail_snippets(),
+                error.help_snippets(),
+            ),
+            Self::NativeFunction { error, .. } => (
+                NativeFunctionError::title(),
+                error.description(),
+                error.detail_snippets(),
+                error.help_snippets(),
+            ),
+        };
         let label = format!("{}: {}", title, description);
         let message = Level::Error
             .title(&label)
@@ -46,30 +59,6 @@ impl<'src> DustError<'src> {
         report
     }
 
-    fn error_data(
-        &self,
-    ) -> (
-        &str,
-        &str,
-        SmallVec<[(String, Span); 2]>,
-        SmallVec<[(String, Span); 2]>,
-    ) {
-        match self {
-            Self::Compile { error, .. } => (
-                CompileError::title(),
-                error.description(),
-                error.detail_snippets(),
-                error.help_snippets(),
-            ),
-            Self::NativeFunction { error, .. } => (
-                NativeFunctionError::title(),
-                error.description(),
-                error.detail_snippets(),
-                error.help_snippets(),
-            ),
-        }
-    }
-
     fn source(&self) -> &str {
         match self {
             Self::Compile { source, .. } => source,

dust-lang/src/instruction/load_function.rs

@@ -44,6 +44,6 @@ impl From<LoadFunction> for Instruction {
 
 impl Display for LoadFunction {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "R{} = P{}", self.destination, self.record_index)
+        write!(f, "R{} = F{}", self.destination, self.record_index)
     }
 }

dust-lang/src/instruction/mod.rs

@@ -105,11 +105,11 @@ mod load_function;
 mod load_list;
 mod load_self;
 mod modulo;
-mod r#move;
 mod multiply;
 mod negate;
 mod not;
 mod operation;
+mod point;
 mod r#return;
 mod set_local;
 mod subtract;
@@ -136,7 +136,7 @@ pub use multiply::Multiply;
 pub use negate::Negate;
 pub use not::Not;
 pub use operation::Operation;
-pub use r#move::Point;
+pub use point::Point;
 pub use r#return::Return;
 pub use set_local::SetLocal;
 pub use subtract::Subtract;
@@ -475,7 +475,8 @@ impl Instruction {
 
     pub fn yields_value(&self) -> bool {
         match self.operation() {
-            Operation::LOAD_BOOLEAN
+            Operation::POINT
+            | Operation::LOAD_BOOLEAN
             | Operation::LOAD_CONSTANT
             | Operation::LOAD_FUNCTION
             | Operation::LOAD_LIST
@@ -488,18 +489,17 @@ impl Instruction {
             | Operation::MODULO
             | Operation::NEGATE
             | Operation::NOT
-            | Operation::EQUAL
-            | Operation::LESS
-            | Operation::LESS_EQUAL
             | Operation::CALL => true,
             Operation::CALL_NATIVE => {
                 let function = NativeFunction::from(self.b_field());
 
                 function.returns_value()
             }
-            Operation::POINT
+            Operation::CLOSE
-            | Operation::CLOSE
             | Operation::SET_LOCAL
+            | Operation::EQUAL
+            | Operation::LESS
+            | Operation::LESS_EQUAL
             | Operation::TEST
             | Operation::TEST_SET
             | Operation::JUMP
@@ -688,17 +688,17 @@ impl Instruction {
             Operation::CALL => {
                 let Call {
                     destination,
-                    function_register: record_index,
+                    function_register,
                     argument_count,
                 } = Call::from(self);
                 let arguments_start = destination.saturating_sub(argument_count);
 
                 match argument_count {
-                    0 => format!("R{destination} = P{record_index}()"),
+                    0 => format!("R{destination} = R{function_register}()"),
-                    1 => format!("R{destination} = P{record_index}(R{arguments_start})"),
+                    1 => format!("R{destination} = R{function_register}(R{arguments_start})"),
                     _ => {
                         format!(
-                            "R{destination} = P{record_index}(R{arguments_start}..R{destination})"
+                            "R{destination} = R{function_register}(R{arguments_start}..R{destination})"
                         )
                     }
                 }

dust-lang/src/instruction/operation.rs

@@ -39,7 +39,7 @@ impl Operation {
 impl Operation {
     pub fn name(&self) -> &'static str {
         match *self {
-            Self::POINT => "MOVE",
+            Self::POINT => "POINT",
             Self::CLOSE => "CLOSE",
             Self::LOAD_BOOLEAN => "LOAD_BOOLEAN",
             Self::LOAD_CONSTANT => "LOAD_CONSTANT",

dust-lang/src/native_function/assertion.rs

@@ -17,7 +17,7 @@ pub fn panic(
         let value = record.open_register(register_index);
 
         if let Some(string) = value.as_string() {
-            message.push_str(&string);
+            message.push_str(string);
             message.push('\n');
         }
     }

dust-lang/src/type.rs

@@ -314,12 +314,12 @@ impl Display for FunctionType {
         write!(f, "(")?;
 
         if let Some(value_parameters) = &self.value_parameters {
-            for (index, (identifier, r#type)) in value_parameters.iter().enumerate() {
+            for (index, (_, r#type)) in value_parameters.iter().enumerate() {
                 if index > 0 {
                     write!(f, ", ")?;
                 }
 
-                write!(f, "{identifier}: {type}")?;
+                write!(f, "{type}")?;
             }
         }
 

dust-lang/src/value/concrete_value.rs

@@ -91,8 +91,16 @@ impl ConcreteValue {
 
                 Integer(sum)
             }
-            (String(left), Character(_)) => todo!(),
+            (String(left), Character(right)) => {
-            (String(left), String(right)) => todo!(),
+                let concatenated = format!("{}{}", left, right);
+
+                String(DustString::from(concatenated))
+            }
+            (String(left), String(right)) => {
+                let concatenated = format!("{}{}", left, right);
+
+                String(DustString::from(concatenated))
+            }
             _ => panic!(
                 "{}",
                 ValueError::CannotAdd(

dust-lang/src/value/function.rs

@@ -8,8 +8,7 @@ use super::DustString;
 pub struct Function {
     pub name: Option<DustString>,
     pub r#type: FunctionType,
-    pub record_index: usize,
+    pub record_index: u8,
-    pub prototype_index: usize,
 }
 
 impl Display for Function {

dust-lang/src/value/mod.rs

@@ -12,7 +12,7 @@ use serde::{Deserialize, Serialize};
 
 use std::fmt::{self, Debug, Display, Formatter};
 
-use crate::{vm::Record, Type, Vm};
+use crate::{vm::Record, Type};
 
 #[derive(Clone, Debug, PartialEq, PartialOrd, Serialize, Deserialize)]
 pub enum Value {
@@ -23,9 +23,6 @@ pub enum Value {
 
     #[serde(skip)]
     Function(Function),
-
-    #[serde(skip)]
-    SelfFunction,
 }
 
 impl Value {
@@ -60,7 +57,6 @@ impl Value {
                 Type::List(Box::new(item_type.clone()))
             }
             Value::Function(Function { r#type, .. }) => Type::Function(Box::new(r#type.clone())),
-            Value::SelfFunction => Type::SelfFunction,
         }
     }
 
@@ -163,7 +159,6 @@ impl Value {
             Value::AbstractList(list) => list.display(record),
             Value::Concrete(concrete_value) => concrete_value.display(),
             Value::Function(function) => DustString::from(function.to_string()),
-            Value::SelfFunction => DustString::from("self"),
         }
     }
 }
@@ -174,7 +169,6 @@ impl Display for Value {
             Value::Concrete(concrete_value) => write!(f, "{concrete_value}"),
             Value::AbstractList(list) => write!(f, "{list}"),
             Value::Function(function) => write!(f, "{function}"),
-            Value::SelfFunction => write!(f, "self"),
         }
     }
 }

dust-lang/src/vm/call_stack.rs

@@ -1,10 +1,12 @@
 use std::fmt::{self, Debug, Display, Formatter};
 
-use super::{FunctionCall, VmError};
+use crate::DustString;
+
+use super::VmError;
 
 #[derive(Clone, PartialEq)]
 pub struct CallStack {
-    pub calls: Vec<FunctionCall>,
+    calls: Vec<FunctionCall>,
 }
 
 impl CallStack {
@@ -47,6 +49,18 @@ impl CallStack {
 
         self.calls.last().unwrap()
     }
+
+    pub fn last_mut_or_panic(&mut self) -> &mut FunctionCall {
+        assert!(!self.is_empty(), "{}", VmError::CallStackUnderflow);
+
+        self.calls.last_mut().unwrap()
+    }
+}
+
+impl Default for CallStack {
+    fn default() -> Self {
+        Self::new()
+    }
 }
 
 impl Debug for CallStack {
@@ -60,9 +74,37 @@ impl Display for CallStack {
         writeln!(f, "-- DUST CALL STACK --")?;
 
         for function_call in &self.calls {
-            writeln!(f, "{function_call:?}")?;
+            writeln!(f, "{function_call}")?;
         }
 
         Ok(())
     }
 }
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct FunctionCall {
+    pub name: Option<DustString>,
+    pub record_index: u8,
+    pub return_register: u8,
+    pub ip: usize,
+}
+
+impl Display for FunctionCall {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        let FunctionCall {
+            name,
+            record_index,
+            return_register,
+            ..
+        } = self;
+        let name = name
+            .as_ref()
+            .map(|name| name.as_str())
+            .unwrap_or("anonymous");
+
+        write!(
+            f,
+            "{name} (Record: {record_index}, Return register: {return_register})"
+        )
+    }
+}

dust-lang/src/vm/error.rs

@@ -1,6 +1,6 @@
 use std::fmt::{self, Display, Formatter};
 
-use crate::{DustString, InstructionData, Value};
+use crate::{InstructionData, Value};
 
 use super::call_stack::CallStack;
 

dust-lang/src/vm/mod.rs

@@ -2,7 +2,7 @@
 mod call_stack;
 mod error;
 mod record;
-mod runner;
+mod run_action;
 mod thread;
 
 use std::{
@@ -11,9 +11,10 @@ use std::{
     thread::spawn,
 };
 
-pub use call_stack::CallStack;
+pub use call_stack::{CallStack, FunctionCall};
 pub use error::VmError;
 pub use record::Record;
+pub use run_action::RunAction;
 pub use thread::{Thread, ThreadSignal};
 
 use crate::{compile, Chunk, DustError, Value};
@@ -92,10 +93,3 @@ impl Display for Pointer {
         }
     }
 }
-
-#[derive(Clone, Debug, PartialEq)]
-pub struct FunctionCall {
-    record_index: usize,
-    return_register: u8,
-    argument_count: u8,
-}

dust-lang/src/vm/record.rs

@@ -2,41 +2,63 @@ use std::mem::replace;
 
 use smallvec::SmallVec;
 
-use crate::{Local, Span, Value};
+use crate::{DustString, Function, FunctionType, Local, Span, Value};
 
-use super::{runner::RunAction, Pointer, Register};
+use super::{run_action::RunAction, Pointer, Register};
 
 pub struct Record {
     pub ip: usize,
     pub actions: SmallVec<[RunAction; 32]>,
-    positions: SmallVec<[Span; 32]>,
 
     stack: Vec<Register>,
+    last_assigned_register: Option<u8>,
+
+    name: Option<DustString>,
+    r#type: FunctionType,
+
+    positions: SmallVec<[Span; 32]>,
     constants: SmallVec<[Value; 16]>,
     locals: SmallVec<[Local; 8]>,
 
-    last_assigned_register: Option<u8>,
+    stack_size: usize,
+    index: u8,
 }
 
 impl Record {
     pub fn new(
-        stack: Vec<Register>,
+        actions: SmallVec<[RunAction; 32]>,
+        last_assigned_register: Option<u8>,
+        name: Option<DustString>,
+        r#type: FunctionType,
+        positions: SmallVec<[Span; 32]>,
         constants: SmallVec<[Value; 16]>,
         locals: SmallVec<[Local; 8]>,
-        actions: SmallVec<[RunAction; 32]>,
+        stack_size: usize,
-        positions: SmallVec<[Span; 32]>,
+        index: u8,
     ) -> Self {
         Self {
             ip: 0,
             actions,
+            stack: vec![Register::Empty; stack_size],
+            last_assigned_register,
+            name,
+            r#type,
             positions,
-            stack,
             constants,
             locals,
-            last_assigned_register: None,
+            stack_size,
+            index,
         }
     }
 
+    pub fn name(&self) -> Option<&DustString> {
+        self.name.as_ref()
+    }
+
+    pub fn index(&self) -> u8 {
+        self.index
+    }
+
     pub fn stack_size(&self) -> usize {
         self.stack.len()
     }
@@ -49,6 +71,14 @@ impl Record {
         self.last_assigned_register
     }
 
+    pub fn as_function(&self) -> Function {
+        Function {
+            name: self.name.clone(),
+            r#type: self.r#type.clone(),
+            record_index: self.index,
+        }
+    }
+
     pub(crate) fn follow_pointer(&self, pointer: Pointer) -> &Value {
         log::trace!("Follow pointer {pointer}");
 

dust-lang/src/vm/run_action.rs

@@ -1,15 +1,12 @@
-use smallvec::SmallVec;
-
 use crate::{
     instruction::{
         Call, CallNative, Close, LoadBoolean, LoadConstant, LoadFunction, LoadList, LoadSelf, Point,
     },
     vm::VmError,
-    AbstractList, ConcreteValue, Function, Instruction, InstructionData, NativeFunction, Type,
+    AbstractList, ConcreteValue, Instruction, InstructionData, Type, Value,
-    Value,
 };
 
-use super::{thread::ThreadSignal, FunctionCall, Pointer, Record, Register};
+use super::{thread::ThreadSignal, Pointer, Record, Register};
 
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub struct RunAction {
@@ -122,6 +119,8 @@ pub fn load_constant(instruction_data: InstructionData, record: &mut Record) ->
     } = instruction_data.into();
     let register = Register::Pointer(Pointer::Constant(constant_index));
 
+    log::trace!("Load constant {constant_index} into R{destination}");
+
     record.set_register(destination, register);
 
     if jump_next {
@@ -170,18 +169,22 @@ pub fn load_list(instruction_data: InstructionData, record: &mut Record) -> Thre
     ThreadSignal::Continue
 }
 
-pub fn load_function(instruction_data: InstructionData, record: &mut Record) -> ThreadSignal {
+pub fn load_function(instruction_data: InstructionData, _: &mut Record) -> ThreadSignal {
     let LoadFunction {
         destination,
         record_index,
     } = instruction_data.into();
 
-    ThreadSignal::Continue
+    ThreadSignal::LoadFunction {
+        from_record_index: record_index,
+        to_register_index: destination,
+    }
 }
 
 pub fn load_self(instruction_data: InstructionData, record: &mut Record) -> ThreadSignal {
     let LoadSelf { destination } = instruction_data.into();
-    let register = Register::Value(Value::SelfFunction);
+    let function = record.as_function();
+    let register = Register::Value(Value::Function(function));
 
     record.set_register(destination, register);
 
@@ -510,9 +513,9 @@ pub fn jump(instruction_data: InstructionData, record: &mut Record) -> ThreadSig
     let is_positive = c != 0;
 
     if is_positive {
-        record.ip += offset + 1
+        record.ip += offset;
     } else {
-        record.ip -= offset
+        record.ip -= offset + 1;
     }
 
     ThreadSignal::Continue
@@ -535,11 +538,11 @@ pub fn call(instruction_data: InstructionData, record: &mut Record) -> ThreadSig
         ),
     };
 
-    ThreadSignal::Call(FunctionCall {
+    ThreadSignal::Call {
         record_index: function.record_index,
         return_register: destination,
         argument_count,
-    })
+    }
 }
 
 pub fn call_native(instruction_data: InstructionData, record: &mut Record) -> ThreadSignal {
@@ -551,12 +554,9 @@ pub fn call_native(instruction_data: InstructionData, record: &mut Record) -> Th
     let first_argument_index = destination - argument_count;
     let argument_range = first_argument_index..destination;
 
-    let function = NativeFunction::from(function);
+    function
-    let thread_signal = function
         .call(record, Some(destination), argument_range)
-        .unwrap_or_else(|error| panic!("{error:?}"));
+        .unwrap_or_else(|error| panic!("{error:?}"))
-
-    thread_signal
 }
 
 pub fn r#return(instruction_data: InstructionData, _: &mut Record) -> ThreadSignal {

dust-lang/src/vm/thread.rs

@@ -1,27 +1,9 @@
-use std::mem::swap;
+use crate::{
+    vm::{FunctionCall, Register},
+    Chunk, DustString, Value,
+};
 
-use crate::{vm::Register, Chunk, Value};
+use super::{record::Record, CallStack, VmError};
-
-use super::{record::Record, runner::RunAction, CallStack, FunctionCall, VmError};
-
-fn create_records(chunk: Chunk, records: &mut Vec<Record>) {
-    let (_, _, instructions, positions, constants, locals, prototypes, stack_size) =
-        chunk.take_data();
-    let actions = instructions.into_iter().map(RunAction::from).collect();
-    let record = Record::new(
-        vec![Register::Empty; stack_size],
-        constants,
-        locals,
-        actions,
-        positions,
-    );
-
-    for chunk in prototypes {
-        create_records(chunk, records);
-    }
-
-    records.push(record);
-}
 
 pub struct Thread {
     call_stack: CallStack,
@@ -33,7 +15,7 @@ impl Thread {
         let call_stack = CallStack::with_capacity(chunk.prototypes().len() + 1);
         let mut records = Vec::with_capacity(chunk.prototypes().len() + 1);
 
-        create_records(chunk, &mut records);
+        chunk.into_records(&mut records);
 
         Thread {
             call_stack,
@@ -42,36 +24,104 @@ impl Thread {
     }
 
     pub fn run(&mut self) -> Option<Value> {
-        let (record, remaining_records) = self.records.split_first_mut().unwrap();
+        let mut active = &mut self.records[0];
+
+        log::info!(
+            "Starting thread with {}",
+            active
+                .as_function()
+                .name
+                .unwrap_or_else(|| DustString::from("anonymous"))
+        );
 
         loop {
             assert!(
-                record.ip < record.actions.len(),
+                active.ip < active.actions.len(),
                 "{}",
                 VmError::InstructionIndexOutOfBounds {
                     call_stack: self.call_stack.clone(),
-                    ip: record.ip,
+                    ip: active.ip,
                 }
             );
 
-            let action = record.actions[record.ip];
+            log::trace!(
-            let signal = (action.logic)(action.data, record);
+                "Run \"{}\" | Record = {} | IP = {}",
+                active
+                    .name()
+                    .cloned()
+                    .unwrap_or_else(|| DustString::from("anonymous")),
+                active.index(),
+                active.ip
+            );
+
+            let action = active.actions[active.ip];
+            let signal = (action.logic)(action.data, active);
+
+            active.ip += 1;
 
             match signal {
-                ThreadSignal::Continue => {
+                ThreadSignal::Continue => {}
-                    record.ip += 1;
+                ThreadSignal::Call {
-                }
+                    record_index,
-                ThreadSignal::Call(function_call) => {
+                    return_register,
-                    swap(record, &mut remaining_records[function_call.record_index]);
+                    argument_count,
+                } => {
+                    let record_index = record_index as usize;
+                    let first_argument_register = return_register - argument_count;
+                    let mut arguments = Vec::with_capacity(argument_count as usize);
+
+                    for register_index in first_argument_register..return_register {
+                        let value = active
+                            .replace_register_or_clone_constant(register_index, Register::Empty);
+
+                        arguments.push(value);
+                    }
+
+                    if record_index == active.index() as usize {
+                        log::trace!("Recursion detected");
+
+                        self.call_stack.last_mut_or_panic().ip = active.ip;
+                        active.ip = 0;
+                    }
+
+                    active = &mut self.records[record_index];
+
+                    for (index, argument) in arguments.into_iter().enumerate() {
+                        active.set_register(index as u8, Register::Value(argument));
+                    }
+
+                    let function_call = FunctionCall {
+                        name: active.name().cloned(),
+                        record_index: active.index(),
+                        return_register,
+                        ip: 0,
+                    };
+
                     self.call_stack.push(function_call);
                 }
+                ThreadSignal::LoadFunction {
+                    from_record_index,
+                    to_register_index,
+                } => {
+                    let function_record_index = from_record_index as usize;
+                    let original_record_index = active.index() as usize;
+
+                    active = &mut self.records[function_record_index];
+
+                    let function = active.as_function();
+                    let register = Register::Value(Value::Function(function));
+
+                    active = &mut self.records[original_record_index];
+
+                    active.set_register(to_register_index, register);
+                }
                 ThreadSignal::Return(should_return_value) => {
                     let returning_call = match self.call_stack.pop() {
                         Some(function_call) => function_call,
                         None => {
                             if should_return_value {
-                                return record.last_assigned_register().map(|register| {
+                                return active.last_assigned_register().map(|register| {
-                                    record.replace_register_or_clone_constant(
+                                    active.replace_register_or_clone_constant(
                                         register,
                                         Register::Empty,
                                     )
@@ -82,19 +132,26 @@ impl Thread {
                         }
                     };
                     let outer_call = self.call_stack.last_or_panic();
+                    let record_index = outer_call.record_index as usize;
+
+                    log::trace!("Return from {returning_call} to {outer_call}");
 
                     if should_return_value {
-                        let return_register = record
+                        let return_register = active
                             .last_assigned_register()
                             .unwrap_or_else(|| panic!("Expected return value"));
-                        let value = record
+                        let return_value = active
                             .replace_register_or_clone_constant(return_register, Register::Empty);
 
-                        swap(record, &mut remaining_records[outer_call.record_index]);
+                        active = &mut self.records[record_index];
 
-                        record.set_register(returning_call.return_register, Register::Value(value));
+                        active.set_register(
+                            returning_call.return_register,
+                            Register::Value(return_value),
+                        );
                     } else {
-                        swap(record, &mut remaining_records[outer_call.record_index]);
+                        active = &mut self.records[record_index];
+                        active.ip = outer_call.ip;
                     }
                 }
             }
@@ -104,6 +161,14 @@ impl Thread {
 
 pub enum ThreadSignal {
     Continue,
-    Call(FunctionCall),
+    Call {
+        record_index: u8,
+        return_register: u8,
+        argument_count: u8,
+    },
     Return(bool),
+    LoadFunction {
+        from_record_index: u8,
+        to_register_index: u8,
+    },
 }

examples/fibonacci.ds

@@ -5,4 +5,4 @@ fn fib (n: int) -> int {
     fib(n - 1) + fib(n - 2)
 }
 
-write_line(fib(25))
+write_line(fib(1))