Fix #835: Haskell quasiquotations

lib/rouge/lexers/haskell.rb

@@ -81,6 +81,15 @@ def self.detect?(text)
 
         rule /\[\s*\]/, Keyword::Type
         rule /\(\s*\)/, Name::Builtin
+
+        # Quasiquotations
+        rule /(\[)([_a-z][\w']*)(\|)/ do |m|
+          token Operator, m[1]
+          token Name, m[2]
+          token Operator, m[3]
+          push :quasiquotation
+        end
+
         rule /[\[\](),;`{}]/, Punctuation
       end
 
@@ -162,6 +171,12 @@ def self.detect?(text)
         rule /./, Error, :pop!
       end
 
+      state :quasiquotation do
+        rule /\|\]/, Operator, :pop!
+        rule /[^\|]+/m, Text
+        rule /\|/, Text
+      end
+
       state :string do
         rule /"/, Str, :pop!
         rule /\\/, Str::Escape, :escape

spec/visual/samples/haskell

@@ -383,3 +383,12 @@ foo = replicate n '\x1f363'
 
 bar :: String
 bar = "\x1f389\x1f363\x1f389"
+
+quasi1 = [quoter|Some quoted text|]
+
+quasi2 = [quoter'|Some text with a | in it|]
+
+quasi3 = [here|Newlines
+are part of
+the quotation
+|]