From be79c58ac13042496ad50b167ab5217296e65150 Mon Sep 17 00:00:00 2001
From: Ben Gamari <ben@smart-cactus.org>
Date: Thu, 1 Nov 2018 13:09:48 -0400
Subject: [PATCH] haskell: Properly highlight promoted data constructors

Unfortunately there is a bit of ambiguity with char literals.
For instance, the data constructor `A'` would be `'A'` in promoted form.
This will still be highlighted as as char literal but this is the best
we can do without more context.
---
 lib/rouge/lexers/haskell.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/rouge/lexers/haskell.rb b/lib/rouge/lexers/haskell.rb
index 72a858035b..e756836731 100644
--- a/lib/rouge/lexers/haskell.rb
+++ b/lib/rouge/lexers/haskell.rb
@@ -61,6 +61,7 @@ def self.detect?(text)
         # rule /^[_a-z][\w']*/, Name::Function
         rule /[_a-z][\w']*/, Name
         rule /[A-Z][\w']*/, Keyword::Type
+        rule /'[A-Z]\w[\w']*/, Keyword::Type  # promoted data constructor
 
         # lambda operator
         rule %r(\\(?![:!#\$\%&*+.\\/<=>?@^\|~-]+)), Name::Function