Improve API and errors

Cargo.lock

@@ -29,6 +29,54 @@ version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0942ffc6dcaadf03badf6e6a2d0228460359d5e34b57ccdc720b7382dfbd5ec5"
 
+[[package]]
+name = "anstream"
+version = "0.6.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d96bd03f33fe50a863e394ee9718a706f988b9079b20c3784fb726e7678b62fb"
+dependencies = [
+ "anstyle",
+ "anstyle-parse",
+ "anstyle-query",
+ "anstyle-wincon",
+ "colorchoice",
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8901269c6307e8d93993578286ac0edf7f195079ffff5ebdeea6a59ffb7e36bc"
+
+[[package]]
+name = "anstyle-parse"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c75ac65da39e5fe5ab759307499ddad880d724eed2f6ce5b5e8a26f4f387928c"
+dependencies = [
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle-query"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e28923312444cdd728e4738b3f9c9cac739500909bb3d3c94b43551b16517648"
+dependencies = [
+ "windows-sys 0.52.0",
+]
+
+[[package]]
+name = "anstyle-wincon"
+version = "3.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1cd54b81ec8d6180e24654d0b371ad22fc3dd083b6ff8ba325b72e00c87660a7"
+dependencies = [
+ "anstyle",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "ariadne"
 version = "0.4.0"
@@ -65,12 +113,68 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b9c28d4e5dd9a9262a38b231153591da6ce1471b818233f4727985d3dd0ed93c"
 dependencies = [
  "hashbrown",
- "regex-automata",
+ "regex-automata 0.3.9",
  "serde",
  "stacker",
  "unicode-ident",
 ]
 
+[[package]]
+name = "clap"
+version = "4.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b230ab84b0ffdf890d5a10abdbc8b83ae1c4918275daea1ab8801f71536b2651"
+dependencies = [
+ "clap_builder",
+ "clap_derive",
+]
+
+[[package]]
+name = "clap_builder"
+version = "4.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae129e2e766ae0ec03484e609954119f123cc1fe650337e155d03b022f24f7b4"
+dependencies = [
+ "anstream",
+ "anstyle",
+ "clap_lex",
+ "strsim",
+]
+
+[[package]]
+name = "clap_derive"
+version = "4.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "307bc0538d5f0f83b8248db3087aa92fe504e4691294d0c96c0eabc33f47ba47"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "clap_lex"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "98cc8fbded0c607b7ba9dd60cd98df59af97e84d24e49c8557331cfc26d301ce"
+
+[[package]]
+name = "colorchoice"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "acbf1af155f9b9ef647e42cdc158db4b64a1b61f743629225fde6f3e0be2a7c7"
+
+[[package]]
+name = "colored"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cbf2150cce219b664a8a70df7a1f933836724b503f8a413af9365b4dcc4d90b8"
+dependencies = [
+ "lazy_static",
+ "windows-sys 0.48.0",
+]
+
 [[package]]
 name = "concolor"
 version = "0.1.1"
@@ -97,6 +201,32 @@ version = "0.5.0"
 dependencies = [
  "ariadne",
  "chumsky",
+ "clap",
+ "colored",
+ "env_logger",
+]
+
+[[package]]
+name = "env_filter"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a009aa4810eb158359dda09d0c87378e4bbb89b5a801f016885a4707ba24f7ea"
+dependencies = [
+ "log",
+ "regex",
+]
+
+[[package]]
+name = "env_logger"
+version = "0.11.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38b35839ba51819680ba087cd351788c9a3c476841207e0b8cee0b04722343b9"
+dependencies = [
+ "anstream",
+ "anstyle",
+ "env_filter",
+ "humantime",
+ "log",
 ]
 
 [[package]]
@@ -109,12 +239,24 @@ dependencies = [
  "allocator-api2",
 ]
 
+[[package]]
+name = "heck"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "95505c38b4572b2d910cecb0281560f54b440a19336cbbcb27bf6ce6adc6f5a8"
+
 [[package]]
 name = "hermit-abi"
 version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bd5256b483761cd23699d0da46cc6fd2ee3be420bbe6d020ae4a091e70b7e9fd"
 
+[[package]]
+name = "humantime"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a3a5bfb195931eeb336b2a7b4d761daec841b97f947d34394601737a7bba5e4"
+
 [[package]]
 name = "is-terminal"
 version = "0.4.12"
@@ -126,12 +268,24 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
 [[package]]
 name = "libc"
 version = "0.2.153"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c198f91728a82281a64e1f4f9eeb25d82cb32a5de251c6bd1b5154d63a8e7bd"
 
+[[package]]
+name = "log"
+version = "0.4.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
+
 [[package]]
 name = "memchr"
 version = "2.7.1"
@@ -171,6 +325,18 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "regex"
+version = "1.10.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b62dbe01f0b06f9d8dc7d49e05a0785f153b00b2c227856282f671e0318c9b15"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata 0.4.6",
+ "regex-syntax 0.8.2",
+]
+
 [[package]]
 name = "regex-automata"
 version = "0.3.9"
@@ -179,7 +345,18 @@ checksum = "59b23e92ee4318893fa3fe3e6fb365258efbfe6ac6ab30f090cdcbb7aa37efa9"
 dependencies = [
  "aho-corasick",
  "memchr",
- "regex-syntax",
+ "regex-syntax 0.7.5",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "86b83b8b9847f9bf95ef68afb0b8e6cdb80f498442f5179a29fad448fcc1eaea"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax 0.8.2",
 ]
 
 [[package]]
@@ -188,6 +365,12 @@ version = "0.7.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dbb5fb1acd8a1a18b3dd5be62d25485eb770e05afb408a9627d14d451bae12da"
 
+[[package]]
+name = "regex-syntax"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08c74e62047bb2de4ff487b251e4a92e24f48745648451635cec7d591162d9f"
+
 [[package]]
 name = "serde"
 version = "1.0.197"
@@ -221,6 +404,12 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "strsim"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ee073c9e4cd00e28217186dbe12796d692868f432bf2e97ee73bed0c56dfa01"
+
 [[package]]
 name = "syn"
 version = "2.0.50"
@@ -244,6 +433,12 @@ version = "0.1.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e51733f11c9c4f72aa0c160008246859e340b00807569a0da0e7a1079b27ba85"
 
+[[package]]
+name = "utf8parse"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "711b9620af191e0cdc7468a8d14e709c3dcdb115b36f838e601583af800a370a"
+
 [[package]]
 name = "version_check"
 version = "0.9.4"
@@ -281,6 +476,15 @@ dependencies = [
  "windows-targets 0.42.2",
 ]
 
+[[package]]
+name = "windows-sys"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "677d2418bec65e3338edb076e806bc1ec15693c5d0104683f2efe857f61056a9"
+dependencies = [
+ "windows-targets 0.48.5",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.52.0"
@@ -305,6 +509,21 @@ dependencies = [
  "windows_x86_64_msvc 0.42.2",
 ]
 
+[[package]]
+name = "windows-targets"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a2fa6e2155d7247be68c096456083145c183cbbbc2764150dda45a87197940c"
+dependencies = [
+ "windows_aarch64_gnullvm 0.48.5",
+ "windows_aarch64_msvc 0.48.5",
+ "windows_i686_gnu 0.48.5",
+ "windows_i686_msvc 0.48.5",
+ "windows_x86_64_gnu 0.48.5",
+ "windows_x86_64_gnullvm 0.48.5",
+ "windows_x86_64_msvc 0.48.5",
+]
+
 [[package]]
 name = "windows-targets"
 version = "0.52.0"
@@ -326,6 +545,12 @@ version = "0.42.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "597a5118570b68bc08d8d59125332c54f1ba9d9adeedeef5b99b02ba2b0698f8"
 
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
+
 [[package]]
 name = "windows_aarch64_gnullvm"
 version = "0.52.0"
@@ -338,6 +563,12 @@ version = "0.42.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e08e8864a60f06ef0d0ff4ba04124db8b0fb3be5776a5cd47641e942e58c4d43"
 
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
+
 [[package]]
 name = "windows_aarch64_msvc"
 version = "0.52.0"
@@ -350,6 +581,12 @@ version = "0.42.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c61d927d8da41da96a81f029489353e68739737d3beca43145c8afec9a31a84f"
 
+[[package]]
+name = "windows_i686_gnu"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
+
 [[package]]
 name = "windows_i686_gnu"
 version = "0.52.0"
@@ -362,6 +599,12 @@ version = "0.42.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "44d840b6ec649f480a41c8d80f9c65108b92d89345dd94027bfe06ac444d1060"
 
+[[package]]
+name = "windows_i686_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
+
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.0"
@@ -374,6 +617,12 @@ version = "0.42.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8de912b8b8feb55c064867cf047dda097f92d51efad5b491dfb98f6bbb70cb36"
 
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
+
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.0"
@@ -386,6 +635,12 @@ version = "0.42.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "26d41b46a36d453748aedef1486d5c7a85db22e56aff34643984ea85514e94a3"
 
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
+
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.0"
@@ -398,6 +653,12 @@ version = "0.42.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9aec5da331524158c6d1a4ac0ab1541149c0b9505fde06423b02f5ef0106b9f0"
 
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.48.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
+
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.0"

Cargo.toml

@@ -15,3 +15,6 @@ opt-level = 3
 [dependencies]
 ariadne = { version = "0.4.0", features = ["auto-color"] }
 chumsky = { version = "1.0.0-alpha.6", features = ["pratt", "label"] }
+clap = { version = "4.5.2", features = ["derive"] }
+colored = "2.1.0"
+env_logger = "0.11.3"

src/error.rs

@@ -1,29 +1,69 @@
 use std::sync::PoisonError;
 
-use chumsky::prelude::Rich;
+use ariadne::{Color, Label, Report, ReportKind};
+use chumsky::{prelude::Rich, span::SimpleSpan};
 
 use crate::{abstract_tree::Type, lexer::Token};
 
 #[derive(Debug, PartialEq)]
-pub enum Error<'src> {
+pub enum Error {
-    Parse(Vec<Rich<'src, Token<'src>>>),
+    Parse {
-    Lex(Vec<Rich<'src, char>>),
+        expected: String,
+        found: Option<String>,
+        span: SimpleSpan,
+    },
+    Lex {
+        expected: String,
+        found: Option<char>,
+        span: SimpleSpan,
+    },
     Runtime(RuntimeError),
 }
 
-impl<'src> From<Vec<Rich<'src, Token<'src>>>> for Error<'src> {
+impl Error {
-    fn from(errors: Vec<Rich<'src, Token<'src>>>) -> Self {
+    pub fn report(&self, source: &str) -> Report {
-        Error::Parse(errors)
+        match self {
+            Error::Parse {
+                expected,
+                found,
+                span,
+            } => Report::build(ReportKind::Custom("Parsing Error", Color::Red), (), 0).finish(),
+            Error::Lex {
+                expected,
+                found,
+                span,
+            } => Report::build(ReportKind::Custom("Lexing Error", Color::Red), (), 0)
+                .with_label(Label::new(span.start..span.end).with_message(format!(
+                    "Exptected {expected} but found {}.",
+                    found.unwrap_or(' '),
+                )))
+                .finish(),
+            Error::Runtime(_) => todo!(),
+        }
     }
 }
 
-impl<'src> From<Vec<Rich<'src, char>>> for Error<'src> {
+impl From<Rich<'_, char>> for Error {
-    fn from(errors: Vec<Rich<'src, char>>) -> Self {
+    fn from(error: Rich<'_, char>) -> Self {
-        Error::Lex(errors)
+        Error::Lex {
+            expected: error.expected().map(|error| error.to_string()).collect(),
+            found: error.reason().found().map(|c| c.clone()),
+            span: error.span().clone(),
+        }
     }
 }
 
-impl<'src> From<RuntimeError> for Error<'src> {
+impl<'src> From<Rich<'_, Token<'src>>> for Error {
+    fn from(error: Rich<'_, Token<'src>>) -> Self {
+        Error::Parse {
+            expected: error.expected().map(|error| error.to_string()).collect(),
+            found: error.reason().found().map(|c| c.to_string()),
+            span: error.span().clone(),
+        }
+    }
+}
+
+impl From<RuntimeError> for Error {
     fn from(error: RuntimeError) -> Self {
         Error::Runtime(error)
     }

src/lexer.rs

@@ -31,11 +31,11 @@ impl<'src> Display for Token<'src> {
     }
 }
 
-pub fn lex<'src>(source: &'src str) -> Result<Vec<(Token, SimpleSpan)>, Error<'src>> {
+pub fn lex<'src>(source: &'src str) -> Result<Vec<(Token<'src>, SimpleSpan)>, Vec<Error>> {
     lexer()
         .parse(source)
         .into_result()
-        .map_err(|error| Error::Lex(error))
+        .map_err(|errors| errors.into_iter().map(|error| error.into()).collect())
 }
 
 pub fn lexer<'src>() -> impl Parser<

src/lib.rs

@@ -5,30 +5,35 @@ pub mod lexer;
 pub mod parser;
 pub mod value;
 
-use abstract_tree::Statement;
+use abstract_tree::AbstractTree;
-use chumsky::{prelude::*, Parser};
 use context::Context;
 use error::Error;
+use lexer::lex;
+pub use parser::{parse, parser, DustParser};
 pub use value::Value;
 
-pub struct Interpreter<P> {
+pub struct Interpreter {
-    _parser: P,
+    context: Context,
-    _context: Context,
 }
 
-impl<'src, P> Interpreter<P>
+impl Interpreter {
-where
+    pub fn new(context: Context) -> Self {
-    P: Parser<'src, &'src str, Statement<'src>, extra::Err<Rich<'src, char>>>,
+        Interpreter { context }
-{
+    }
-    pub fn run(&self, _source: &'src str) -> Result<Value, Error<'src>> {
-        todo!();
 
-        // let final_value = self
+    pub fn run(&mut self, source: &str) -> Result<Value, Vec<Error>> {
-        //     .parser
+        let tokens = lex(source)?;
-        //     .parse(source)
+        let statements = parse(&tokens)?;
-        //     .into_result()?
-        //     .run(&self.context)?;
 
-        // Ok(final_value)
+        let mut value = Value::none();
+
+        for (statement, _span) in statements {
+            value = match statement.run(&self.context) {
+                Ok(value) => value,
+                Err(runtime_error) => return Err(vec![Error::Runtime(runtime_error)]),
+            }
+        }
+
+        Ok(value)
     }
 }

src/main.rs

@@ -0,0 +1,61 @@
+//! Command line interface for the dust programming language.
+
+use ariadne::Source;
+use clap::Parser;
+use colored::Colorize;
+
+use std::{fs::read_to_string, io::Write};
+
+use dust_lang::{context::Context, Interpreter};
+
+/// Command-line arguments to be parsed.
+#[derive(Parser, Debug)]
+#[command(author, version, about, long_about = None)]
+struct Args {
+    /// Dust source code to evaluate.
+    #[arg(short, long)]
+    command: Option<String>,
+
+    /// Location of the file to run.
+    path: Option<String>,
+}
+
+fn main() {
+    env_logger::Builder::from_env("DUST_LOG")
+        .format(|buffer, record| {
+            let args = record.args();
+            let log_level = record.level().to_string().bold();
+            let timestamp = buffer.timestamp_seconds().to_string().dimmed();
+
+            writeln!(buffer, "[{log_level} {timestamp}] {args}")
+        })
+        .init();
+
+    let args = Args::parse();
+    let context = Context::new();
+
+    let source = if let Some(path) = &args.path {
+        read_to_string(path).unwrap()
+    } else if let Some(command) = args.command {
+        command
+    } else {
+        String::with_capacity(0)
+    };
+
+    let mut interpreter = Interpreter::new(context);
+
+    let eval_result = interpreter.run(&source);
+
+    match eval_result {
+        Ok(value) => {
+            if !value.is_none() {
+                println!("{value}")
+            }
+        }
+        Err(errors) => {
+            for error in errors {
+                error.report(&source).eprint(Source::from(&source)).unwrap();
+            }
+        }
+    }
+}

src/parser.rs

@@ -4,24 +4,27 @@ use chumsky::{input::SpannedInput, pratt::*, prelude::*};
 
 use crate::{abstract_tree::*, error::Error, lexer::Token};
 
-type ParserInput<'tokens, 'src> =
+pub type DustParser<'src> = Boxed<
-    SpannedInput<Token<'src>, SimpleSpan, &'tokens [(Token<'src>, SimpleSpan)]>;
+    'src,
+    'src,
+    ParserInput<'src>,
+    Vec<(Statement<'src>, SimpleSpan)>,
+    extra::Err<Rich<'src, Token<'src>, SimpleSpan>>,
+>;
 
-pub fn parse<'tokens, 'src: 'tokens>(
+pub type ParserInput<'src> =
-    tokens: &'tokens [(Token<'src>, SimpleSpan)],
+    SpannedInput<Token<'src>, SimpleSpan, &'src [(Token<'src>, SimpleSpan)]>;
-) -> Result<Vec<(Statement<'src>, SimpleSpan)>, Error<'tokens>> {
+
+pub fn parse<'src>(
+    tokens: &'src [(Token<'src>, SimpleSpan)],
+) -> Result<Vec<(Statement<'src>, SimpleSpan)>, Vec<Error>> {
     parser()
-        .parse(tokens.spanned((0..0).into()))
+        .parse(tokens.spanned((tokens.len()..tokens.len()).into()))
         .into_result()
-        .map_err(|error| Error::Parse(error))
+        .map_err(|errors| errors.into_iter().map(|error| error.into()).collect())
 }
 
-fn parser<'tokens, 'src: 'tokens>() -> impl Parser<
+pub fn parser<'src>() -> DustParser<'src> {
-    'tokens,
-    ParserInput<'tokens, 'src>,
-    Vec<(Statement<'src>, SimpleSpan)>,
-    extra::Err<Rich<'tokens, Token<'src>, SimpleSpan>>,
-> {
     let identifiers: RefCell<HashMap<&str, Identifier>> = RefCell::new(HashMap::new());
 
     let identifier = select! {
@@ -185,6 +188,7 @@ fn parser<'tokens, 'src: 'tokens>() -> impl Parser<
         .map_with(|item, state| (item, state.span()))
         .repeated()
         .collect()
+        .boxed()
 }
 
 #[cfg(test)]
@@ -512,7 +516,8 @@ mod tests {
     fn positive_integer() {
         for i in 0..10 {
             let source = i.to_string();
-            let statements = parse(&lex(&source).unwrap()).unwrap();
+            let tokens = lex(&source).unwrap();
+            let statements = parse(&tokens).unwrap();
 
             assert_eq!(
                 statements[0].0,
@@ -537,7 +542,8 @@ mod tests {
     fn negative_integer() {
         for i in -9..1 {
             let source = i.to_string();
-            let statements = parse(&lex(&source).unwrap()).unwrap();
+            let tokens = lex(&source).unwrap();
+            let statements = parse(&tokens).unwrap();
 
             assert_eq!(
                 statements[0].0,

src/value.rs

@@ -1,6 +1,7 @@
 use std::{
     cmp::Ordering,
     collections::BTreeMap,
+    fmt::{self, Display, Formatter},
     ops::Range,
     sync::{Arc, OnceLock},
 };
@@ -9,6 +10,15 @@ use crate::{abstract_tree::Identifier, error::ValidationError};
 
 pub static NONE: OnceLock<Value> = OnceLock::new();
 
+fn get_none<'a>() -> &'a Value {
+    NONE.get_or_init(|| {
+        Value(Arc::new(ValueInner::Enum(
+            Identifier::new("Option"),
+            Identifier::new("None"),
+        )))
+    })
+}
+
 #[derive(Clone, Debug, PartialEq)]
 pub struct Value(Arc<ValueInner>);
 
@@ -18,13 +28,7 @@ impl Value {
     }
 
     pub fn none() -> Self {
-        NONE.get_or_init(|| {
+        get_none().clone()
-            Value(Arc::new(ValueInner::Enum(
-                Identifier::new("Option"),
-                Identifier::new("None"),
-            )))
-        })
-        .clone()
     }
 
     pub fn boolean(boolean: bool) -> Self {
@@ -66,6 +70,27 @@ impl Value {
 
         Err(ValidationError::ExpectedBoolean)
     }
+
+    pub fn is_none(&self) -> bool {
+        self == get_none()
+    }
+}
+
+impl Display for Value {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        use ValueInner::*;
+
+        match self.inner().as_ref() {
+            Boolean(boolean) => write!(f, "{boolean}"),
+            Float(float) => write!(f, "{float}"),
+            Integer(integer) => write!(f, "{integer}"),
+            List(_) => todo!(),
+            Map(_) => todo!(),
+            Range(_) => todo!(),
+            String(_) => todo!(),
+            Enum(_, _) => todo!(),
+        }
+    }
 }
 
 impl Eq for Value {}