[#565] Change type hint operator from as to ::

Author: jonhue

common/enums.ts

@@ -3,7 +3,7 @@ export enum Prec {
   SubtractionType = -1,
   UnionType = 0,
   Assignment = 1,
-  TypeHint = 1,
+  TypeHint = 0,
   CurriedType = 1,
   NamedInfixApplication = 1,
   SectionIdentifier = 1,

common/terms.ts

@@ -472,7 +472,7 @@ export const type_hint = <RuleName extends string>(
 ) =>
   prec.left(
     Prec.TypeHint,
-    seq(field('value', $._term), 'as', field('type', $._type)),
+    seq(field('value', $._term), '::', field('type', $._type)),
   )
 
 export const hole = <RuleName extends string>($: GrammarSymbols<RuleName>) =>

tony/corpus/terms.txt

@@ -1084,15 +1084,22 @@ type GreaterThan<T>(x :: T) = [y :: T | y > x]
 type hint
 ==================
 
-'string' as String
+'string' :: String
+x :: Promise<Number>
 
 ---
 
 (program
   term: (type_hint
     value: (string)
     type: (parametric_type
-      name: (type))))
+      name: (type)))
+  term: (type_hint
+    value: (identifier)
+    type: (parametric_type
+      name: (type)
+      argument: (parametric_type
+        name: (type)))))
 
 ==================
 hole