Fix type checker for range operator

Author: antonmedv

checker/checker.go

@@ -253,7 +253,7 @@ func (v *visitor) BinaryNode(node *ast.BinaryNode) reflect.Type {
 
 	case "..":
 		if isInteger(l) && isInteger(r) {
-			return arrayType
+			return reflect.SliceOf(integerType)
 		}
 
 	default:
@@ -501,8 +501,7 @@ func (v *visitor) BuiltinNode(node *ast.BuiltinNode) reflect.Type {
 			closure.NumOut() == 1 &&
 			closure.NumIn() == 1 && isInterface(closure.In(0)) {
 
-			return reflect.ArrayOf(0, closure.Out(0))
-
+			return reflect.SliceOf(closure.Out(0))
 		}
 		panic(v.error(node.Arguments[1], "closure should has one input and one output param"))
 

checker/checker_test.go

@@ -158,6 +158,7 @@ func TestCheck(t *testing.T) {
 		"Variadic('', 1, 2) + Variadic('')",
 		"Foo.Variadic('', 1, 2) + Foo.Variadic('')",
 		"count(1..30, {# % 3 == 0}) > 0",
+		"map(1..3, {#}) == [1,2,3]",
 	}
 	for _, test := range typeTests {
 		var err error