better support for aliased type

Author: aspeddro

grammar.js

@@ -313,6 +313,7 @@ module.exports = grammar({
       $._inline_type,
       $.variant_type,
       $.record_type,
+      $.as_aliasing_type,
     ),
 
     _inline_type: $ => choice(
@@ -375,7 +376,6 @@ module.exports = grammar({
       optional('|'),
       barSep1($.polyvar_declaration),
       ']',
-      optional($.as_aliasing_type)
     )),
 
     polyvar_declaration: $ => prec.right(
@@ -417,7 +417,6 @@ module.exports = grammar({
         seq('..', commaSept($._object_type_field)),
       ),
       '}',
-      optional($.as_aliasing_type)
     )),
 
     _object_type_field: $ => alias($.object_type_field, $.field),
@@ -436,7 +435,6 @@ module.exports = grammar({
     generic_type: $ => prec.left(seq(
       $._type_identifier,
       $.type_arguments,
-      optional($.as_aliasing_type)
     )),
 
     type_arguments: $ => seq(
@@ -734,7 +732,7 @@ module.exports = grammar({
       optional($.type_annotation)
     )),
 
-    as_aliasing_type: $ => seq('as', $.type_identifier),
+    as_aliasing_type: $ => seq($._type, 'as', $.type_identifier),
 
     assert_expression: $ => prec.left(seq('assert', $.expression)),
 

test/corpus/type_declarations.txt

@@ -264,12 +264,13 @@ type t<'w> = [M.t<'w>]
     (type_binding
       (type_identifier)
       (type_parameters (type_identifier))
-      (polyvar_type
-        (decorator (decorator_identifier))
-        (polyvar_declaration (polyvar_identifier))
-        (polyvar_declaration (polyvar_identifier))
-        (polyvar_declaration (polyvar_identifier))
-        (as_aliasing_type (type_identifier)))))
+      (as_aliasing_type
+        (polyvar_type
+          (decorator (decorator_identifier))
+          (polyvar_declaration (polyvar_identifier))
+          (polyvar_declaration (polyvar_identifier))
+          (polyvar_declaration (polyvar_identifier)))
+          (type_identifier))))
 
   (type_declaration
     (type_binding
@@ -368,9 +369,10 @@ type t<'a> = {.."name": string} as 'a
     (type_binding
       (type_identifier)
       (type_parameters (type_identifier))
-      (object_type
-        (field (property_identifier (string_fragment)) (type_identifier))
-        (as_aliasing_type (type_identifier))))))
+      (as_aliasing_type
+        (object_type
+          (field (property_identifier (string_fragment)) (type_identifier)))
+          (type_identifier)))))
 
 ===========================================
 Generic
@@ -403,10 +405,11 @@ type t<'a> = generic<'a> as 's
     (type_binding
       (type_identifier)
       (type_parameters (type_identifier))
-      (generic_type
-        (type_identifier)
-        (type_arguments (type_identifier))
-        (as_aliasing_type (type_identifier))))))
+      (as_aliasing_type
+        (generic_type
+          (type_identifier)
+          (type_arguments (type_identifier)))
+          (type_identifier)))))
 
 ===========================================
 Recursive