Fix #175 (unicode forall syntax)

Author: sheaf

CHANGELOG.md

@@ -6,6 +6,8 @@
 - Recognize indented `\begin{code}` boundary in literate haskell files.
 - Fix highlighting of symbolic data constructors within fixity declarations (e.g. `infixl 9 :$`).
 - Add `meta.embedded.block.{quasi-quoter}` scope to quasi-quotations.
+- Ensure highlighting of unicode forall syntax matches that of alphabetic forall syntax
+  ([#175](https://github.com/JustusAdam/language-haskell/issues/175)).
 
 ## 3.3.0 - 25.06.2020
 

syntaxes/haskell.YAML-tmLanguage

@@ -1402,7 +1402,8 @@ repository:
     patterns:
       # Fully reserved symbols,
       # not including '::' (special treatment as it starts type highlighting),
-      # nor '=>' (it highlights its precedent as a type).
+      # nor '=>' (it highlights its precedent as a type),
+      # nor '∀' (highlights subsequent dot for quantification).
       - match: >-
           (?x)
             (?<![\p{S}\p{P}&&[^(),;\[\]`{}_"'']])
@@ -1418,7 +1419,6 @@ repository:
               |(-<<|⤛)
               |(>-|⤚)
               |(>>-|⤜)
-              |(∀)
             )
             (?![\p{S}\p{P}&&[^(),;\[\]`{}_"'']])
         captures:
@@ -1433,7 +1433,6 @@ repository:
           '9': {name: keyword.operator.arrow.left.tail.double.haskell}
           '10': {name: keyword.operator.arrow.tail.haskell}
           '11': {name: keyword.operator.arrow.tail.double.haskell}
-          '12': {name: keyword.other.forall.haskell}
       # Reserved postfix symbol: '#'
       # This allows users to specify highlighting of '#' dependent on theme,
       # as we are unfortunately unable to make a decision based on enabled extensions.
@@ -1501,10 +1500,27 @@ repository:
           '4': {name: storage.type.infix.haskell}
           '5': {name: punctuation.backtick.haskell}
   forall:
-    begin: '\b(?<!'')(forall|∀)\b(?!'')'
+    begin: >-
+      (?x)
+        # Alphabetic forall
+        (?:
+        \b(?<!')
+        (forall)
+        \b(?!')
+        )
+        |
+        # Symbolic forall
+        (?:
+        # Not preceded by a symbol except reserved symbols
+        (?<![\p{S}\p{P}&&[^(),;\[\]`{}_"'']])
+        (∀)
+        # Not followed by a symbol except reserved symbols
+        (?![\p{S}\p{P}&&[^(),;\[\]`{}_"'']])
+        )
     end: '(\.)|(->|→)'
     beginCaptures: 
       '1': {name: keyword.other.forall.haskell}
+      '2': {name: keyword.other.forall.haskell}
     endCaptures:
       '1': {name: keyword.operator.period.haskell}
       '2': {name: keyword.operator.arrow.haskell}

test/tickets/T0175.hs

@@ -0,0 +1,14 @@
+-- SYNTAX TEST "source.haskell" "Unicode forall"
+
+foo :: (∀ a. Num a => a -> a) -> (Int,Double) -> (Int,Double)
+--      ^ keyword.other.forall.haskell
+--         ^ keyword.operator.period.haskell
+foo f (a,b) = (f a, f b)
+
+bar :: (forall a. Num a => a -> a) -> (Int,Double) -> (Int,Double)
+--      ^^^^^^ keyword.other.forall.haskell
+--              ^ keyword.operator.period.haskell
+bar f (a,b) = (f a, f b)
+
+notForall :: x ∀∀ y -> z
+--             ^^ - keyword.other.forall.haskell