diff --git a/corpus/edigits_like.langexp b/corpus/edigits_like.langexp
index 14275bf..a41c95c 100644
--- a/corpus/edigits_like.langexp
+++ b/corpus/edigits_like.langexp
@@ -257,14 +257,17 @@ test_k 'n 'k : Int Int -> Bool = {
     (simple_name_identifier)
     (argument_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
+    (function_type
+      (simple_type
+        (simple_type_identifier))
+      (simple_type
+        (simple_type_identifier))
+      (reference_type
+        (simple_type
+          (simple_type_identifier)))
+      (reference_type
+        (simple_type
+          (simple_type_identifier))))
     (block
       (empty_lines)
       (condition
@@ -355,10 +358,12 @@ test_k 'n 'k : Int Int -> Bool = {
   (function_definition
     (simple_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
+    (function_type
+      (simple_type
+        (simple_type_identifier))
+      (reference_type
+        (simple_type
+          (simple_type_identifier))))
     (block
       (empty_lines)
       (match
@@ -450,12 +455,14 @@ test_k 'n 'k : Int Int -> Bool = {
     (simple_name_identifier)
     (argument_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
+    (function_type
+      (simple_type
+        (simple_type_identifier))
+      (simple_type
+        (simple_type_identifier))
+      (reference_type
+        (simple_type
+          (simple_type_identifier))))
     (block
       (empty_lines)
       (condition
diff --git a/corpus/test.langexp b/corpus/test.langexp
index 91494a2..edfb5ff 100644
--- a/corpus/test.langexp
+++ b/corpus/test.langexp
@@ -230,7 +230,7 @@ result_func! 'a 'b -> 'c -> 'd = ?? 'a == 0 => error "some error" !!=> ('c := 'a
 tuple_argument_test 'x : (A & B & C) = do_something;
 
 // ((A1 & A2) | B | C) same to Variant[Tuple[A1 A2] B C]
-variant_argument_test 'x : ((A1 & A2) | B | C) = do_something;
+variant_argument_test 'x : ( (A1 & A2) | B | C) = do_something;
 
 literals_test = {
   %float_number_literal := 1.0f;
@@ -247,6 +247,10 @@ literals_test = {
   %null_literal := null;
 }
 
+array_argument_test 'x 'y : [[ Int ]] = do_something;
+
+functional_arguments_test 'x 'y : (( Int -> Int )) (( Float <- Float -> Float )) = do_something;
+
 --------------------------------------------------------------------------------
 
 (source_file
@@ -441,11 +445,13 @@ literals_test = {
         (index_literal)))
     (simple_name_identifier)
     (argument_name_identifier)
-    (annotation_identifier)
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
+    (function_type
+      (annotation_identifier)
+      (simple_type
+        (simple_type_identifier))
+      (reference_type
+        (simple_type
+          (simple_type_identifier))))
     (match
       (name_expression
         (argument_name_identifier))
@@ -783,10 +789,11 @@ literals_test = {
       (info))
     (simple_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (simple_type_identifier)
+    (reference_type
       (simple_type
-        (argument_type_identifier)))
+        (simple_type_identifier)
+        (simple_type
+          (argument_type_identifier))))
     (block
       (empty_lines)
       (match
@@ -856,10 +863,11 @@ literals_test = {
       (info))
     (simple_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (simple_type_identifier)
+    (reference_type
       (simple_type
-        (argument_type_identifier)))
+        (simple_type_identifier)
+        (simple_type
+          (argument_type_identifier))))
     (block
       (empty_lines)
       (match
@@ -1094,10 +1102,13 @@ literals_test = {
     (simple_name_identifier)
     (argument_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (argument_type_identifier))
-    (simple_type
-      (argument_type_identifier))
+    (function_type
+      (reference_type
+        (simple_type
+          (argument_type_identifier)))
+      (reference_type
+        (simple_type
+          (argument_type_identifier))))
     (comma_expression
       (comma_expression
         (match
@@ -1150,12 +1161,16 @@ literals_test = {
     (definition_info
       (info))
     (simple_name_identifier)
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
+    (function_type
+      (reference_type
+        (simple_type
+          (simple_type_identifier)))
+      (reference_type
+        (simple_type
+          (simple_type_identifier)))
+      (reference_type
+        (simple_type
+          (simple_type_identifier))))
     (operator_expression
       (operator_expression
         (name_expression
@@ -1172,8 +1187,9 @@ literals_test = {
       (info))
     (simple_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (simple_type_identifier))
+    (reference_type
+      (simple_type
+        (simple_type_identifier)))
     (match
       (name_expression
         (argument_name_identifier))
@@ -1187,12 +1203,16 @@ literals_test = {
     (simple_name_identifier)
     (argument_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
+    (function_type
+      (reference_type
+        (simple_type
+          (simple_type_identifier)))
+      (reference_type
+        (simple_type
+          (simple_type_identifier)))
+      (reference_type
+        (simple_type
+          (simple_type_identifier))))
     (constructor
       (simple_type
         (simple_type_identifier))
@@ -1207,12 +1227,16 @@ literals_test = {
     (simple_name_identifier)
     (argument_name_identifier)
     (argument_name_identifier)
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier))
+    (function_type
+      (reference_type
+        (simple_type
+          (simple_type_identifier)))
+      (reference_type
+        (simple_type
+          (simple_type_identifier)))
+      (reference_type
+        (simple_type
+          (simple_type_identifier))))
     (constructor
       (simple_type
         (simple_type_identifier))
@@ -1227,10 +1251,12 @@ literals_test = {
   (empty_lines)
   (function_definition
     (simple_name_identifier)
-    (simple_type
-      (simple_type_identifier))
-    (simple_type
-      (simple_type_identifier)))
+    (function_type
+      (simple_type
+        (simple_type_identifier))
+      (reference_type
+        (simple_type
+          (simple_type_identifier)))))
   (empty_lines)
   (function_definition
     (definition_info
@@ -1454,4 +1480,37 @@ literals_test = {
         (case
           (null_literal)))
       (empty_lines)))
+  (empty_lines)
+  (function_definition
+    (simple_name_identifier)
+    (argument_name_identifier)
+    (argument_name_identifier)
+    (array_type
+      (simple_type
+        (simple_type_identifier)))
+    (name_expression
+      (simple_name_identifier)))
+  (empty_lines)
+  (function_definition
+    (simple_name_identifier)
+    (argument_name_identifier)
+    (argument_name_identifier)
+    (function_type
+      (function_type
+        (simple_type
+          (simple_type_identifier))
+        (reference_type
+          (simple_type
+            (simple_type_identifier))))
+      (function_type
+        (simple_type
+          (simple_type_identifier))
+        (reference_type
+          (simple_type
+            (simple_type_identifier)))
+        (reference_type
+          (simple_type
+            (simple_type_identifier)))))
+    (name_expression
+      (simple_name_identifier)))
   (empty_lines))
diff --git a/grammar.js b/grammar.js
index 9c74322..cbaa085 100644
--- a/grammar.js
+++ b/grammar.js
@@ -53,11 +53,7 @@ module.exports = grammar({
       )),
       optional(seq(
         ':',
-        repeat1(seq(
-          optional($.annotation_identifier),
-          optional($._reference),
-          $._scoped_type,
-        )),
+        choice($.function_type, $._annotated_type),
       )),
       choice(seq('=', choice(prec(2, choice($.block, $.array)), seq($._super_expression, ';'))), ';'),
     ),
@@ -226,6 +222,11 @@ module.exports = grammar({
       repeat1(seq('&', $._annotated_type)),
     ),
 
+    function_type: $ => seq(
+      $._annotated_type,
+      repeat1($._annotated_type),
+    ),
+
     // add annotations to in all types ??
     _annotated_type: $ => seq(optional($.annotation_identifier), $._scoped_type),
 
@@ -249,6 +250,7 @@ module.exports = grammar({
       $.array_type,
       $.variant_type,
       $.tuple_type,
+      $.function_type,
     ),
 
     _scoped_type: $ => choice(
@@ -259,7 +261,9 @@ module.exports = grammar({
       seq('(', choice(
         $.variant_type,
         $.tuple_type,
+        //$.function_type,
       ), ')'),
+      seq('((', $.function_type, '))'),
     ),
 
     // --- comments