Restrict character literals to one character, allow names to start with 0-2 quotes in haskell-indentation

Author: RafaelBocquet

haskell-indentation.el

@@ -1180,15 +1180,15 @@ the current buffer."
   "Skip to the next token."
   (let ((case-fold-search nil))
 
-    (if (or (looking-at "\"\\([^\\\"]\\|\\\\.\\)*\"")
+    (if (or (looking-at "'\\([^\\']\\|\\\\.\\)'")
+            (looking-at "\"\\([^\\\"]\\|\\\\.\\)*\"")
             (looking-at         ; Hierarchical names always start with uppercase
-             "[[:upper:]]\\(\\s_\\|\\sw\\|'\\)*\\(\\.\\(\\s_\\|\\sw\\|'\\)+\\)*")
-            (looking-at "\\(\\s_\\|\\sw\\)\\(\\s_\\|\\sw\\|'\\)*") ; Only unqualified vars can start with lowercase
+             "'?'?[[:upper:]]\\(\\s_\\|\\sw\\|'\\)*\\(\\.\\(\\s_\\|\\sw\\|'\\)+\\)*")
+            (looking-at "'?'?\\(\\s_\\|\\sw\\)\\(\\s_\\|\\sw\\|'\\)*") ; Only unqualified vars can start with lowercase
             (looking-at "[0-9][0-9oOxXeE+-]*")
             (looking-at "[-:!#$%&*+./<=>?@\\\\^|~]+")
             (looking-at "[](){}[,;]")
-            (looking-at "`[[:alnum:]']*`")
-            (looking-at "'\\([^\\']\\|\\\\.\\)*'"))
+            (looking-at "`[[:alnum:]']*`"))
         (goto-char (match-end 0))
       ;; otherwise skip until space found
       (skip-syntax-forward "^-"))

tests/haskell-indentation-tests.el

@@ -423,9 +423,16 @@ Example of lines:
    "      , baz = 0"
    "      ^"))
 
-(ert-deftest haskell-indentation-check-22 ()
-  "layout versus comma in braces (unicode)"
+(ert-deftest haskell-indentation-check-22a ()
+  "names starting with quotes"
   (haskell-indentation-check
    "f = a (a 'A)"
    "    (a 'A)"
    "^   ^"))
+
+(ert-deftest haskell-indentation-check-22b ()
+  "character literal (escape sequence)"
+  (haskell-indentation-check
+   "f = '\\\\"
+   ""
+   "^   ^"))