conlang: Single-expression functions

compiler/cl-ast/src/ast.rs

@@ -146,7 +146,7 @@ pub struct Function {
     pub name: Sym,
     pub sign: TyFn,
     pub bind: Vec<Param>,
-    pub body: Option<Block>,
+    pub body: Option<Expr>,
 }
 
 /// A single parameter for a [Function]

compiler/cl-ast/src/ast_visitor/fold.rs

@@ -107,7 +107,7 @@ pub trait Fold {
             name: self.fold_sym(name),
             sign: self.fold_ty_fn(sign),
             bind: bind.into_iter().map(|p| self.fold_param(p)).collect(),
-            body: body.map(|b| self.fold_block(b)),
+            body: body.map(|b| self.fold_expr(b)),
         }
     }
     fn fold_param(&mut self, p: Param) -> Param {

compiler/cl-ast/src/ast_visitor/visit.rs

@@ -85,7 +85,7 @@ pub trait Visit<'a>: Sized {
         self.visit_ty_fn(sign);
         bind.iter().for_each(|p| self.visit_param(p));
         if let Some(b) = body {
-            self.visit_block(b)
+            self.visit_expr(b)
         }
     }
     fn visit_param(&mut self, p: &'a Param) {

compiler/cl-interpret/src/function/collect_upvars.rs

@@ -71,7 +71,7 @@ impl<'a> Visit<'a> for CollectUpvars<'_> {
             self.bind_name(name);
         }
         if let Some(body) = body {
-            self.visit_block(body);
+            self.visit_expr(body);
         }
     }
 

compiler/cl-parser/src/parser.rs

@@ -459,12 +459,11 @@ impl Parse<'_> for Function {
             sign,
             bind,
             body: match p.peek_kind(P)? {
-                TokenKind::LCurly => Some(Block::parse(p)?),
                 TokenKind::Semi => {
                     p.consume_peeked();
                     None
                 }
-                t => Err(p.error(Unexpected(t), P))?,
+                _ => Some(Expr::parse(p)?),
             },
         })
     }

compiler/cl-typeck/src/stage/populate.rs

@@ -108,7 +108,7 @@ impl<'a> Visit<'a> for Populator<'_, 'a> {
         self.visit_ty_fn(sign);
         bind.iter().for_each(|p| self.visit_param(p));
         if let Some(b) = body {
-            self.visit_block(b)
+            self.visit_expr(b)
         }
     }
 

grammar.ebnf

@@ -26,7 +26,7 @@ Static      = "static" Mutability Identifier ':' Ty '=' Expr ';' ;
 Module      = "mod" Identifier ModuleKind ;
 ModuleKind  = '{' Item* '}' | ';' ;
 
-Function    = "fn" Identifier '(' (Param ',')* Param? ')' ('->' Ty)? Block? ;
+Function    = "fn" Identifier '(' (Param ',')* Param? ')' ('->' Ty)? (Expr | ';') ;
 Param       = Mutability Identifier ':' Ty ;
 
 Struct      = "struct" Identifier (StructTuple | StructBody)?;
@@ -127,6 +127,17 @@ Block       = '{' Stmt* '}';
 Group       = Empty | '(' (Expr | Tuple) ')' ;
 Tuple       = (Expr ',')* Expr? ;
 
+
+Match       = "match" { (MatchArm ',')* MatchArm? } ;
+MatchArm    = Pattern '=>' Expr ;
+Pattern     = Path
+            | Literal
+            | '&' "mut"? Pattern
+            | '(' (Pattern ',')* (Pattern | '..' )? ')'
+            | '[' (Pattern ',')* (Pattern | '..' Identifier?)? ']'
+            | StructPattern
+            ;
+
 Loop        = "loop"  Block ;
 While       = "while" Expr Block Else ;
 If          = "if"    Expr Block Else ;