add return type support and enhance parameter parsing

crates/mitki-parse/src/grammar/items.rs

@@ -29,6 +29,11 @@ fn item(p: &mut Parser) {
                 p.error("expected function parameters");
             }
 
+            if p.at(COLON) {
+                let m = p.start();
+                types::ascription(p);
+                m.complete(p, RETURN_TYPE);
+            }
             exprs::block(p);
 
             m.complete(p, FN);
@@ -74,8 +79,23 @@ fn param_list(p: &mut Parser) {
     p.advance();
 
     while !matches!(p.peek_kind(), RIGHT_PAREN | EOF) {
+        if p.peek_kind() != NAME {
+            p.error_and_bump("expected parameter name");
+            if p.eat(COMMA) {
+                continue;
+            }
+            break;
+        }
+
         param(p);
-        p.eat(COMMA);
+
+        if !p.eat(COMMA) {
+            if p.peek_kind() == NAME {
+                p.expect(COMMA);
+            } else {
+                break;
+            }
+        }
     }
 
     p.expect(RIGHT_PAREN);
@@ -84,14 +104,13 @@ fn param_list(p: &mut Parser) {
 
 fn param(p: &mut Parser) {
     let m = p.start();
-    p.advance();
+    name(p, &[]);
 
     if p.at(COLON) {
         types::ascription(p);
     } else {
         p.error("missing type for function parameter");
     }
 
-    p.advance();
     m.complete(p, PARAM);
 }

crates/mitki-parse/test_data/curly_in_params.ir

@@ -5,14 +5,13 @@ MODULE
       NAME: "foo"
     PARAM_LIST
       LEFT_PAREN: "("
-      PARAM
-        RIGHT_BRACE: "}"
-        RIGHT_PAREN: ")"
-      PARAM
-        LEFT_BRACE: "{"
-        RIGHT_BRACE: "}"
+  RIGHT_BRACE: "}"
+  RIGHT_PAREN: ")"
+  LEFT_BRACE: "{"
+  RIGHT_BRACE: "}"
 
 Errors:
-  missing type for function parameter
-  missing type for function parameter
-  expected `)`
+  expected parameter name
+  expected item
+  expected item
+  expected item

crates/mitki-parse/test_data/function_ret_type.ir

@@ -0,0 +1,27 @@
+MODULE
+  FN
+    FUN_KW: "fun"
+    IDENT
+      NAME: "foo"
+    PARAM_LIST
+      LEFT_PAREN: "("
+      RIGHT_PAREN: ")"
+    STMT_LIST
+      LEFT_BRACE: "{"
+      RIGHT_BRACE: "}"
+  FN
+    FUN_KW: "fun"
+    IDENT
+      NAME: "bar"
+    PARAM_LIST
+      LEFT_PAREN: "("
+      RIGHT_PAREN: ")"
+    RETURN_TYPE
+      COLON: ":"
+      PATH_TYPE
+        NAME: "u32"
+    STMT_LIST
+      LEFT_BRACE: "{"
+      RIGHT_BRACE: "}"
+
+Errors:

crates/mitki-parse/test_data/function_ret_type.mitki

@@ -0,0 +1,2 @@
+fun foo() {}
+fun bar(): u32 {}

crates/mitki-parse/test_data/missing_fn_param_type.ir

@@ -0,0 +1,35 @@
+MODULE
+  FN
+    FUN_KW: "fun"
+    IDENT
+      NAME: "f"
+    PARAM_LIST
+      LEFT_PAREN: "("
+      PARAM
+        IDENT
+          NAME: "x"
+      PARAM
+        IDENT
+          NAME: "y"
+        COLON: ":"
+        PATH_TYPE
+          NAME: "i32"
+      COMMA: ","
+      PARAM
+        IDENT
+          NAME: "z"
+      COMMA: ","
+      PARAM
+        IDENT
+          NAME: "t"
+        COLON: ":"
+        PATH_TYPE
+          NAME: "i32"
+      RIGHT_PAREN: ")"
+    STMT_LIST
+      LEFT_BRACE: "{"
+      RIGHT_BRACE: "}"
+
+Errors:
+  missing type for function parameter
+  missing type for function parameter

crates/mitki-parse/test_data/missing_fn_param_type.mitki

@@ -0,0 +1 @@
+fun f(x y: i32, z, t: i32) {}

crates/mitki-parse/test_data/param_list.ir

@@ -0,0 +1,46 @@
+MODULE
+  FN
+    FUN_KW: "fun"
+    IDENT
+      NAME: "a"
+    PARAM_LIST
+      LEFT_PAREN: "("
+      RIGHT_PAREN: ")"
+    STMT_LIST
+      LEFT_BRACE: "{"
+      RIGHT_BRACE: "}"
+  FN
+    FUN_KW: "fun"
+    IDENT
+      NAME: "b"
+    PARAM_LIST
+      LEFT_PAREN: "("
+      PARAM
+        IDENT
+          NAME: "x"
+        COLON: ":"
+        PATH_TYPE
+          NAME: "i32"
+      RIGHT_PAREN: ")"
+    STMT_LIST
+      LEFT_BRACE: "{"
+      RIGHT_BRACE: "}"
+  FN
+    FUN_KW: "fun"
+    IDENT
+      NAME: "c"
+    PARAM_LIST
+      LEFT_PAREN: "("
+      PARAM
+        IDENT
+          NAME: "x"
+        COLON: ":"
+        PATH_TYPE
+          NAME: "i32"
+      COMMA: ","
+      RIGHT_PAREN: ")"
+    STMT_LIST
+      LEFT_BRACE: "{"
+      RIGHT_BRACE: "}"
+
+Errors:

crates/mitki-parse/test_data/param_list.mitki

@@ -0,0 +1,3 @@
+fun a() {}
+fun b(x: i32) {}
+fun c(x: i32, ) {}

crates/mitki-yellow/src/syntax_kind.rs

@@ -40,6 +40,7 @@ pub enum SyntaxKind {
     EXPR_STMT,
     FIELD_EXPR,
     FN,
+    RETURN_TYPE,
     IDENT,
     TYPE_PARAM,
     LITERAL,