From 3693d5127d09360676f4387ffc873e555e7ea04a Mon Sep 17 00:00:00 2001
From: Gracjan Polak <gracjanpolak@gmail.com>
Date: Tue, 31 May 2016 18:47:52 +0200
Subject: [PATCH 1/2] Track parens by our own in type highlight

---
 haskell-font-lock.el | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/haskell-font-lock.el b/haskell-font-lock.el
index b557003ae..4cf707ce7 100644
--- a/haskell-font-lock.el
+++ b/haskell-font-lock.el
@@ -240,7 +240,8 @@ like ::, class, instance, data, newtype, type."
         (token nil)
         ;; we are starting right after ::
         (last-token-was-operator t)
-        (last-token-was-newline nil))
+        (last-token-was-newline nil)
+        (open-parens 0))
     (while cont
       (setq token (haskell-lexeme-looking-at-token 'newline))
 
@@ -251,9 +252,26 @@ like ::, class, instance, data, newtype, type."
         (setq last-token-was-newline (not last-token-was-operator))
         (setq end (match-end 0))
         (goto-char (match-end 0)))
+       ((member (match-string-no-properties 0)
+                    '(")" "]" "}"))
+        (setq open-parens (1- open-parens))
+        (if (< open-parens 0)
+            ;; unmatched closing parenthesis closes type declaration
+            (setq cont nil)
+          (setq end (match-end 0))
+          (goto-char end))
+        (setq last-token-was-newline nil))
+       ((and (member (match-string-no-properties 0)
+                     '("," ";" "|"))
+             (not (member (match-string-no-properties 0) ignore)))
+        (if (equal 0 open-parens)
+            (setq cont nil)
+          (setq last-token-was-operator t)
+          (setq end (match-end 0))
+          (goto-char end))
+        (setq last-token-was-newline nil))
        ((and (or (member (match-string-no-properties 0)
-                         '("<-" "=" "<-" "←"  "," ";"
-                           ")" "]" "}" "|"))
+                         '("<-" "=" "←"))
                  (member (match-string-no-properties 0) haskell-font-lock--reverved-ids))
              (not (member (match-string-no-properties 0) ignore)))
         (setq cont nil)
@@ -262,11 +280,9 @@ like ::, class, instance, data, newtype, type."
                 '("(" "[" "{"))
         (if last-token-was-newline
             (setq cont nil)
-          (goto-char (match-beginning 0))
-          (condition-case err
-                (forward-sexp)
-              (scan-error (goto-char (nth 3 err))))
-          (setq end (point))
+          (setq open-parens (1+ open-parens))
+          (setq end (match-end 0))
+          (goto-char end)
           (setq last-token-was-newline nil)))
        ((member token '(qsymid char string number template-haskell-quote template-haskell-quasi-quote))
         (setq last-token-was-operator (member (haskell-lexeme-classify-by-first-char (char-after (match-beginning 1)))

From f9c8624c1f2f9b873074396f62dd40b0afbb6faa Mon Sep 17 00:00:00 2001
From: Gracjan Polak <gracjanpolak@gmail.com>
Date: Tue, 31 May 2016 18:55:49 +0200
Subject: [PATCH 2/2] Add tests for types and parens

---
 tests/haskell-font-lock-tests.el | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tests/haskell-font-lock-tests.el b/tests/haskell-font-lock-tests.el
index 0ae72c5d2..e6a287458 100644
--- a/tests/haskell-font-lock-tests.el
+++ b/tests/haskell-font-lock-tests.el
@@ -878,6 +878,16 @@
      ("Z" t haskell-type-face)
      ("C" t haskell-constructor-face))))
 
+(ert-deftest haskell-type-colors-31 ()
+  (check-properties
+   ;; open parentheses do not keep type decl open because there might
+   ;; be an unclosed parenthesis stretching to the end of file and
+   ;; that is very costly to check
+   '("x :: (OpenParen"
+     "   NotType)")
+   '(("OpenParen" t haskell-type-face)
+     ("NotType" t haskell-constructor-face))))
+
 (ert-deftest haskell-pattern ()
   "Fontify the \"pattern\" keyword in contexts related to pattern synonyms."
   :expected-result :failed