const 和 var 支持冒号分隔符

_examples/hello/src/main.wa

@@ -18,8 +18,8 @@ import (
 	heart()
 }
 
-fn sum(n int) => int {
-	var v int
+fn sum(n: int) => int {
+	var v: int
 	for i := 1; i <= n; i++ {
 		v += i
 	}

hello.wa

@@ -2,10 +2,9 @@
 
 fn main() {
 	println("凹凹，吃了吗")
-	println(answer())
+	println(add(40, 2))
 }
 
-fn answer() => (x:int) {
-	x = 40 + 2
-	return
+fn add(a:i32, b:i32) => i32 {
+	return a + b
 }

internal/parser/parser.go

@@ -2244,6 +2244,11 @@ func (p *parser) parseValueSpec(doc *ast.CommentGroup, keyword token.Token, iota
 
 	pos := p.pos
 	idents := p.parseIdentList()
+	var colonPos token.Pos
+	if p.tok == token.COLON {
+		colonPos = p.pos
+		p.next()
+	}
 	typ := p.tryType()
 	var values []ast.Expr
 	// always permit optional initialization for more tolerant parsing
@@ -2269,11 +2274,12 @@ func (p *parser) parseValueSpec(doc *ast.CommentGroup, keyword token.Token, iota
 	// the end of the innermost containing block.
 	// (Global identifiers are resolved in a separate phase after parsing.)
 	spec := &ast.ValueSpec{
-		Doc:     doc,
-		Names:   idents,
-		Type:    typ,
-		Values:  values,
-		Comment: p.lineComment,
+		Doc:      doc,
+		Names:    idents,
+		ColonPos: colonPos,
+		Type:     typ,
+		Values:   values,
+		Comment:  p.lineComment,
 	}
 	kind := ast.Con
 	if keyword == token.VAR {