uh

Cargo.lock

@@ -11,6 +11,15 @@ dependencies = [
  "const-random",
 ]
 
+[[package]]
+name = "ariadne"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7080ae01b2f0c312065d4914cd0f0de045eb8832e9415b355106a6cff3073cb4"
+dependencies = [
+ "yansi",
+]
+
 [[package]]
 name = "beef"
 version = "0.5.1"
@@ -81,6 +90,7 @@ dependencies = [
 name = "lambda-calculus"
 version = "0.1.0"
 dependencies = [
+ "ariadne",
  "chumsky",
  "logos",
 ]
@@ -188,3 +198,9 @@ name = "wasi"
 version = "0.10.2+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
+
+[[package]]
+name = "yansi"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fc79f4a1e39857fc00c3f662cbf2651c771f00e9c15fe2abc341806bd46bd71"

Cargo.toml

@@ -6,5 +6,6 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+ariadne = "0.1.3"
 chumsky = "0.7.0"
 logos = "0.12.0"

src/lib.rs

@@ -1,9 +1,12 @@
+use ariadne::{Color, Fmt, Label, Report, ReportKind, Source};
+use chumsky::{Parser, Stream};
 use logos::Logos;
 
 mod lexer {
     use logos::Logos;
+    use std::fmt::Formatter;
 
-    #[derive(Logos, Clone, Eq, PartialEq, Hash)]
+    #[derive(Logos, Debug, Clone, Eq, PartialEq, Hash)]
     pub enum Token<'a> {
         #[token("λ")]
         Lambda,
@@ -27,56 +30,138 @@ mod lexer {
         #[regex(r"[ \t\r\n]+", logos::skip)]
         Error,
     }
+
+    impl std::fmt::Display for Token<'_> {
+        fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+            match self {
+                Token::Lambda => write!(f, "λ"),
+                Token::Dot => write!(f, "."),
+                Token::Binding => write!(f, ":="),
+                Token::ParenO => write!(f, "("),
+                Token::ParenC => write!(f, ")"),
+                Token::Ident(ident) => write!(f, "{}", ident),
+                Token::Error => write!(f, "[error]"),
+            }
+        }
+    }
 }
 
 mod parser {
     use crate::lexer::Token;
     use chumsky::prelude::*;
 
-    enum Expr {
+    #[derive(Debug)]
+    pub enum Expr {
         Name(String),
         Application {
             function: Box<Expr>,
             argument: Box<Expr>,
         },
         Abstraction {
-            args: Vec<String>,
-            body: Expr,
+            args: Vec<char>,
+            body: Box<Expr>,
         },
     }
 
-    fn expr_parser<'a>() -> impl Parser<Token<'a>, Spanned<Expr>, Error = Simple<Token<'a>>> + Clone
-    {
+    pub fn expr_parser<'a>() -> impl Parser<Token<'a>, Expr, Error = Simple<Token<'a>>> + Clone {
         recursive(|expr| {
-            let variable = filter_map(|span, token| match token {
-                Token::Ident(name) => Ok(Expr::Name(name.to_string())),
+            let ident = filter_map(|span, token| match token {
+                Token::Ident(ident) => Ok(ident.to_string()),
                 _ => Err(Simple::expected_input_found(span, [], Some(token))),
             })
-            .labelled("variable");
+            .labelled("ident");
 
             let abstraction = just(Token::Lambda)
-                .ignore_then(variable)
-                .then(Token::Dot)
-                .then(expr.clone());
+                .ignore_then(ident)
+                .then_ignore(just(Token::Dot))
+                .then(expr)
+                .map(|(args, body)| Expr::Abstraction {
+                    args: args.chars().collect(),
+                    body: Box::new(body),
+                })
+                .labelled("abstraction");
 
-            let application = just(expr).then(expr.clone());
-
-            let atom = variable
-                .or(expr.delimited_by(Token::ParenO, Token::ParenC))
-                .or(abstraction)
-                .or(application);
-
-            let binding = just(variable)
-                .then_ignore(Token::Binding)
-                .then(expr.clone());
-
-            let statement = just(expr.clone()).or(binding);
-
-            todo!()
+            abstraction
         })
     }
 }
 
 pub fn run(input: &str) {
-    let mut lex = lexer::Token::lexer(input);
+    let mut lexer = lexer::Token::lexer(input);
+    let length = lexer.source().len();
+
+    match parser::expr_parser().parse(Stream::from_iter(length..length + 1, lexer.spanned())) {
+        Ok(ast) => println!("parsed: {ast:#?}"),
+        Err(errs) => errs
+            .into_iter()
+            .map(|e| e.map(|c| c.to_string()))
+            .for_each(|e| {
+                let report = Report::build(ReportKind::Error, (), e.span().start);
+
+                let report = match e.reason() {
+                    chumsky::error::SimpleReason::Unclosed { span, delimiter } => report
+                        .with_message(format!(
+                            "Unclosed delimiter {}",
+                            delimiter.fg(Color::Yellow)
+                        ))
+                        .with_label(
+                            Label::new(span.clone())
+                                .with_message(format!(
+                                    "Unclosed delimiter {}",
+                                    delimiter.fg(Color::Yellow)
+                                ))
+                                .with_color(Color::Yellow),
+                        )
+                        .with_label(
+                            Label::new(e.span())
+                                .with_message(format!(
+                                    "Must be closed before this {}",
+                                    e.found()
+                                        .unwrap_or(&"end of file".to_string())
+                                        .fg(Color::Red)
+                                ))
+                                .with_color(Color::Red),
+                        ),
+                    chumsky::error::SimpleReason::Unexpected => report
+                        .with_message(format!(
+                            "{}, expected {}",
+                            if e.found().is_some() {
+                                "Unexpected token in input"
+                            } else {
+                                "Unexpected end of input"
+                            },
+                            if e.expected().len() == 0 {
+                                "something else".to_string()
+                            } else {
+                                e.expected()
+                                    .map(|expected| match expected {
+                                        Some(expected) => expected.to_string(),
+                                        None => "end of input".to_string(),
+                                    })
+                                    .collect::<Vec<_>>()
+                                    .join(", ")
+                            }
+                        ))
+                        .with_label(
+                            Label::new(e.span())
+                                .with_message(format!(
+                                    "Unexpected token {}",
+                                    e.found()
+                                        .unwrap_or(&"end of file".to_string())
+                                        .fg(Color::Red)
+                                ))
+                                .with_color(Color::Red),
+                        ),
+                    chumsky::error::SimpleReason::Custom(msg) => {
+                        report.with_message(msg).with_label(
+                            Label::new(e.span())
+                                .with_message(format!("{}", msg.fg(Color::Red)))
+                                .with_color(Color::Red),
+                        )
+                    }
+                };
+
+                report.finish().print(Source::from(input)).unwrap();
+            }),
+    }
 }

src/main.rs

@@ -1,3 +1,6 @@
 fn main() {
-    lambda_calculus::run("hello");
+    lambda_calculus::run("λa.a");
+    // lambda_calculus::run("λa.a");
+    // lambda_calculus::run("λab.a");
+    // lambda_calculus::run("U := λab.a");
 }