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Merged
thsfranca merged 1 commit into from
Mar 21, 2026
Merged

feat: self-host cond macro, remove Expr::Cond from compiler #156

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35 changes: 0 additions & 35 deletions src/ast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,13 +42,6 @@ pub struct Binding {
pub span: Span,
}

#[derive(Debug, Clone, PartialEq)]
pub struct CondClause {
pub test: Expr,
pub value: Expr,
pub span: Span,
}

#[derive(Debug, Clone, PartialEq)]
pub enum Pattern {
Wildcard(Span),
Expand Down Expand Up @@ -96,12 +89,6 @@ pub enum Expr {
span: Span,
},

Cond {
clauses: Vec<CondClause>,
else_body: Option<Box<Expr>>,
span: Span,
},

Let {
bindings: Vec<Binding>,
body: Vec<Expr>,
Expand Down Expand Up @@ -182,7 +169,6 @@ impl Expr {
| Expr::Symbol(_, s)
| Expr::Keyword(_, s) => *s,
Expr::If { span, .. }
| Expr::Cond { span, .. }
| Expr::Let { span, .. }
| Expr::Lambda { span, .. }
| Expr::Call { span, .. }
Expand Down Expand Up @@ -328,27 +314,6 @@ mod tests {
assert!(matches!(expr, Expr::If { .. }));
}

#[test]
fn cond_expr() {
let expr = Expr::Cond {
clauses: vec![CondClause {
test: Expr::Bool(true, span(6, 10)),
value: Expr::Int(1, span(11, 12)),
span: span(6, 12),
}],
else_body: Some(Box::new(Expr::Int(0, span(19, 20)))),
span: span(0, 21),
};
assert_eq!(expr.span(), span(0, 21));
if let Expr::Cond {
clauses, else_body, ..
} = &expr
{
assert_eq!(clauses.len(), 1);
assert!(else_body.is_some());
}
}

#[test]
fn let_expr() {
let expr = Expr::Let {
Expand Down
119 changes: 8 additions & 111 deletions src/macro_expand.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ use crate::ast::{self, Binding, Expr, TopForm};
use crate::diagnostics::Diagnostic;
use crate::lexer;
use crate::parser;
use crate::source::{FileId, Span};
use crate::source::FileId;
use crate::types::{SyntaxValue, expr_to_syntax, syntax_to_expr};

const MAX_EXPANSION_DEPTH: usize = 64;
Expand Down Expand Up @@ -153,12 +153,6 @@ fn expand_expr(
}

match expr {
Expr::Cond {
clauses,
else_body,
span,
} => expand_cond(clauses, else_body, span, registry, diagnostics, depth),

Expr::Call { func, args, span } => {
if let Expr::Symbol(ref name, _) = *func
&& let Some(macro_def) = registry.get(name.as_str())
Expand Down Expand Up @@ -724,31 +718,6 @@ fn rename_syntax_fn(items: Vec<SyntaxValue>, renames: &HashMap<String, String>)
SyntaxValue::List(result)
}

fn expand_cond(
clauses: Vec<ast::CondClause>,
else_body: Option<Box<Expr>>,
span: Span,
registry: &HashMap<String, MacroDef>,
diagnostics: &mut Vec<Diagnostic>,
depth: usize,
) -> Expr {
let mut result = match else_body {
Some(e) => expand_expr(*e, registry, diagnostics, depth),
None => Expr::Nil(span),
};

for clause in clauses.into_iter().rev() {
result = Expr::If {
test: Box::new(expand_expr(clause.test, registry, diagnostics, depth)),
then_branch: Box::new(expand_expr(clause.value, registry, diagnostics, depth)),
else_branch: Box::new(result),
span,
};
}

result
}

#[cfg(test)]
mod tests {
use super::*;
Expand All @@ -758,77 +727,6 @@ mod tests {
Span::new(FileId::new(0), start, end)
}

#[test]
fn expand_cond_to_nested_if() {
let input = vec![TopForm::Expr(Expr::Cond {
clauses: vec![
ast::CondClause {
test: Expr::Bool(true, span(0, 4)),
value: Expr::Int(1, span(5, 6)),
span: span(0, 6),
},
ast::CondClause {
test: Expr::Bool(false, span(7, 12)),
value: Expr::Int(2, span(13, 14)),
span: span(7, 14),
},
],
else_body: Some(Box::new(Expr::Int(3, span(21, 22)))),
span: span(0, 23),
})];

let (result, diags) = expand(input);
assert!(diags.is_empty());
if let TopForm::Expr(Expr::If {
test,
then_branch,
else_branch,
..
}) = &result[0]
{
assert!(matches!(test.as_ref(), Expr::Bool(true, _)));
assert!(matches!(then_branch.as_ref(), Expr::Int(1, _)));
assert!(matches!(else_branch.as_ref(), Expr::If { .. }));

if let Expr::If {
test: inner_test,
then_branch: inner_then,
else_branch: inner_else,
..
} = else_branch.as_ref()
{
assert!(matches!(inner_test.as_ref(), Expr::Bool(false, _)));
assert!(matches!(inner_then.as_ref(), Expr::Int(2, _)));
assert!(matches!(inner_else.as_ref(), Expr::Int(3, _)));
} else {
panic!("expected nested if");
}
} else {
panic!("expected if expression");
}
}

#[test]
fn expand_cond_no_else() {
let input = vec![TopForm::Expr(Expr::Cond {
clauses: vec![ast::CondClause {
test: Expr::Bool(true, span(0, 4)),
value: Expr::Int(1, span(5, 6)),
span: span(0, 6),
}],
else_body: None,
span: span(0, 7),
})];

let (result, diags) = expand(input);
assert!(diags.is_empty());
if let TopForm::Expr(Expr::If { else_branch, .. }) = &result[0] {
assert!(matches!(else_branch.as_ref(), Expr::Nil(_)));
} else {
panic!("expected if expression");
}
}

#[test]
fn expand_and_to_if() {
let input = vec![TopForm::Expr(Expr::Call {
Expand Down Expand Up @@ -951,14 +849,13 @@ mod tests {
name: "test".into(),
params: vec![],
return_type: None,
body: vec![Expr::Cond {
clauses: vec![ast::CondClause {
test: Expr::Bool(true, span(0, 4)),
value: Expr::Int(1, span(5, 6)),
span: span(0, 6),
}],
else_body: Some(Box::new(Expr::Int(0, span(13, 14)))),
span: span(0, 15),
body: vec![Expr::Call {
func: Box::new(Expr::Symbol("and".into(), span(1, 4))),
args: vec![
Expr::Bool(true, span(5, 9)),
Expr::Bool(false, span(10, 15)),
],
span: span(0, 16),
}],
span: span(0, 20),
}];
Expand Down
85 changes: 22 additions & 63 deletions src/parser.rs
View file
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Original file line number Diff line number Diff line change
@@ -1,6 +1,4 @@
use crate::ast::{
Binding, CondClause, Expr, Field, MatchClause, Param, Pattern, TopForm, TypeExpr, Variant,
};
use crate::ast::{Binding, Expr, Field, MatchClause, Param, Pattern, TopForm, TypeExpr, Variant};
use crate::diagnostics::{Diagnostic, Label};
use crate::lexer::{Token, TokenKind};
use crate::source::{FileId, Span};
Expand Down Expand Up @@ -420,7 +418,6 @@ impl<'a> Parser<'a> {
match name.as_str() {
"if" => return self.parse_if(open_span),
"let" => return self.parse_let(open_span),
"cond" => return self.parse_cond(open_span),
"match" => return self.parse_match(open_span),
"fn" => return self.parse_lambda(open_span),
"spawn" => return self.parse_spawn(open_span),
Expand Down Expand Up @@ -609,34 +606,6 @@ impl<'a> Parser<'a> {
Some(body)
}

fn parse_cond(&mut self, open_span: Span) -> Option<Expr> {
self.pos += 1;

let mut clauses = Vec::new();
let mut else_body = None;

while !self.at_end() && !self.check(|k| matches!(k, TokenKind::RightParen)) {
if self.check(|k| matches!(k, TokenKind::Keyword(s) if s == "else")) {
self.pos += 1;
else_body = Some(Box::new(self.parse_expr()?));
break;
}

let test = self.parse_expr()?;
let value = self.parse_expr()?;
let span = Span::new(test.span().file, test.span().start, value.span().end);
clauses.push(CondClause { test, value, span });
}

let close_span = self.expect_right_paren(open_span)?;

Some(Expr::Cond {
clauses,
else_body,
span: Span::new(open_span.file, open_span.start, close_span.end),
})
}

fn parse_match(&mut self, open_span: Span) -> Option<Expr> {
self.pos += 1;

Expand Down Expand Up @@ -1402,54 +1371,44 @@ mod tests {
}

#[test]
fn cond_basic() {
fn cond_parses_as_call() {
let (forms, diags) = parse_source("(cond (< x 0) \"neg\" (> x 0) \"pos\")");
assert!(diags.is_empty());
if let TopForm::Expr(Expr::Cond {
clauses, else_body, ..
}) = &forms[0]
{
assert_eq!(clauses.len(), 2);
assert!(matches!(&clauses[0].test, Expr::Call { .. }));
assert!(matches!(&clauses[0].value, Expr::String(s, _) if s == "neg"));
assert!(matches!(&clauses[1].test, Expr::Call { .. }));
assert!(matches!(&clauses[1].value, Expr::String(s, _) if s == "pos"));
assert!(else_body.is_none());
if let TopForm::Expr(Expr::Call { func, args, .. }) = &forms[0] {
assert!(matches!(func.as_ref(), Expr::Symbol(s, _) if s == "cond"));
assert_eq!(args.len(), 4);
assert!(matches!(&args[0], Expr::Call { .. }));
assert!(matches!(&args[1], Expr::String(s, _) if s == "neg"));
assert!(matches!(&args[2], Expr::Call { .. }));
assert!(matches!(&args[3], Expr::String(s, _) if s == "pos"));
} else {
panic!("expected cond expression");
panic!("expected call expression");
}
}

#[test]
fn cond_with_else() {
fn cond_with_else_parses_as_call() {
let (forms, diags) = parse_source("(cond (< x 0) \"neg\" :else \"zero\")");
assert!(diags.is_empty());
if let TopForm::Expr(Expr::Cond {
clauses, else_body, ..
}) = &forms[0]
{
assert_eq!(clauses.len(), 1);
assert!(else_body.is_some());
assert!(
matches!(else_body.as_ref().unwrap().as_ref(), Expr::String(s, _) if s == "zero")
);
if let TopForm::Expr(Expr::Call { func, args, .. }) = &forms[0] {
assert!(matches!(func.as_ref(), Expr::Symbol(s, _) if s == "cond"));
assert_eq!(args.len(), 4);
assert!(matches!(&args[2], Expr::Keyword(s, _) if s == "else"));
assert!(matches!(&args[3], Expr::String(s, _) if s == "zero"));
} else {
panic!("expected cond expression");
panic!("expected call expression");
}
}

#[test]
fn cond_empty() {
fn cond_empty_parses_as_call() {
let (forms, diags) = parse_source("(cond)");
assert!(diags.is_empty());
if let TopForm::Expr(Expr::Cond {
clauses, else_body, ..
}) = &forms[0]
{
assert!(clauses.is_empty());
assert!(else_body.is_none());
if let TopForm::Expr(Expr::Call { func, args, .. }) = &forms[0] {
assert!(matches!(func.as_ref(), Expr::Symbol(s, _) if s == "cond"));
assert!(args.is_empty());
} else {
panic!("expected cond expression");
panic!("expected call expression");
}
}

Expand Down
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