Merge pull request #1321 from gracjan/pr-liquid

Add LiquidHaskell annotation highlight

Author: gracjan

haskell-font-lock.el

@@ -155,7 +155,13 @@ font faces assigned as if respective mode was enabled."
 ;;;###autoload
 (defface haskell-pragma-face
   '((t :inherit font-lock-preprocessor-face))
-  "Face used to highlight Haskell pragmas."
+  "Face used to highlight Haskell pragmas ({-# ... #-})."
+  :group 'haskell-appearance)
+
+;;;###autoload
+(defface haskell-liquid-haskell-annotation-face
+  '((t :inherit haskell-pragma-face))
+  "Face used to highlight LiquidHaskell annotations ({-@ ... @-})."
   :group 'haskell-appearance)
 
 ;;;###autoload
@@ -512,14 +518,23 @@ like ::, class, instance, data, newtype, type."
       (equal (string-to-syntax "<") (syntax-after (point))))
     'haskell-literate-comment-face)
    ;; Detect pragmas. A pragma is enclosed in special comment
-   ;; delimeters {-# .. #-}.
+   ;; delimiters {-# .. #-}.
    ((save-excursion
       (goto-char (nth 8 state))
       (and (looking-at-p "{-#")
            (forward-comment 1)
            (goto-char (- (point) 3))
            (looking-at-p "#-}")))
     'haskell-pragma-face)
+   ;; Detect Liquid Haskell annotations enclosed in special comment
+   ;; delimiters {-@ .. @-}.
+   ((save-excursion
+      (goto-char (nth 8 state))
+      (and (looking-at-p "{-@")
+           (forward-comment 1)
+           (goto-char (- (point) 3))
+           (looking-at-p "@-}")))
+    'haskell-liquid-haskell-annotation-face)
    ;; Haddock comment start with either "-- [|^*$]" or "{- ?[|^*$]"
    ;; (note space optional for nested comments and mandatory for
    ;; double dash comments).

tests/haskell-font-lock-tests.el

@@ -155,6 +155,9 @@
      "{-# pragma1 #-}"
      "{-# non_pragma2 -}"
      "{- non_pragma3 #-}"
+     "{-@ liquid_haskell @-}"
+     "{-@ non_liquid_haskell_2 -}"
+     "{- non_liquid_haskell_3 @-}"
      )
    '(("Cons0" "w" haskell-constructor-face)
      ("Comm1" "w" font-lock-comment-face)
@@ -168,7 +171,11 @@
      ("pragma1"  "w" haskell-pragma-face)
      ("non_pragma2"  "w" font-lock-comment-face)
 
-     ("non_pragma3" "w" font-lock-comment-face))))
+     ("non_pragma3" "w" font-lock-comment-face)
+     ("liquid_haskell"  "w" haskell-liquid-haskell-annotation-face)
+     ("non_liquid_haskell_2"  "w" font-lock-comment-face)
+
+     ("non_liquid_haskell_3" "w" font-lock-comment-face))))
 
 
 (ert-deftest haskell-syntactic-string-vs-comment-escape ()