font-lock: cover more operators than just the builtins

For example, the tuple construction `1 /\ 2` was weirdly
half-haighlighted before this commit, because it wasn't covered by the
"operators regexp" and was getting caught by some other rule. Fix that.

For inspiration, I looked at the regexp from the official Atom
purescript highlight
https://github.com/purescript-contrib/atom-language-purescript/blob/d17eee55b12c140e8a1a750cce7e5aa9b09653c2/src/purescript.coffee#L32
that one works a bit differently, it excludes chars from class. AFAIK
Emacs can't do that, so instead I just enlisted the symbols. One thing
I did differently though is including colon, because it is a valid
operator in PureScript (for List), I think Atom has a bug in their
regexp.

Author: Hi-Angel

purescript-font-lock.el

@@ -165,12 +165,10 @@ Returns keywords suitable for `font-lock-keywords'."
           ;; be thrown for some reason by backslash's escape syntax.
           "\\(\\s_\\|\\\\\\)+")
 
-         ;; Reserved operations
-         (reservedsym
+         (operator
           (concat "\\S_"
-                  ;; (regexp-opt '(".." "::" "=" "\\" "|" "<-" "->"
-                  ;;            "@" "~" "=>") t)
-                  "\\(->\\|\\.\\.\\|::\\|∷\\|<-\\|=>\\|[=@\\|~]\\)"
+                  ;; All punctuation, excluding (),;[]{}_"'`
+                  "\\([!@#$%^&*+\\-./<=>?@|~:∷\\\\]+\\)"
                   "\\S_"))
          ;; These are only keywords when appear at top-level, optionally with
          ;; indentation. They are not reserved and in other levels would represent
@@ -210,7 +208,7 @@ Returns keywords suitable for `font-lock-keywords'."
       ;;
       (,toplevel-keywords 1 (symbol-value 'purescript-keyword-face))
       (,reservedid 1 (symbol-value 'purescript-keyword-face))
-      (,reservedsym 1 (symbol-value 'purescript-operator-face))
+      (,operator 1 (symbol-value 'purescript-operator-face))
       ;; Special case for `as', `hiding', `safe' and `qualified', which are
       ;; keywords in import statements but are not otherwise reserved.
       ("\\<import[ \t]+\\(?:\\(safe\\>\\)[ \t]*\\)?\\(?:\\(qualified\\>\\)[ \t]*\\)?[^ \t\n()]+[ \t]*\\(?:\\(\\<as\\>\\)[ \t]*[^ \t\n()]+[ \t]*\\)?\\(\\<hiding\\>\\)?"

tests/purescript-font-lock-tests.el

@@ -271,33 +271,33 @@ derive newtype instance foldableNonEmptyList :: Foldable NonEmptyList
      (70 70 font-lock-builtin-face) (71 71 nil)
      (72 83 font-lock-type-face) (84 85 nil)
      (86 86 font-lock-keyword-face) (87 87 nil)
-     (88 89 font-lock-type-face) (90 95 nil)
+     (88 89 font-lock-builtin-face) (90 95 nil)
      (96 96 font-lock-builtin-face) (97 101 nil)
      (102 113 font-lock-type-face) (114 119 nil)
-     (120 121 font-lock-type-face) (122 137 nil)
-     (138 138 font-lock-type-face) (139 139 nil)
+     (120 121 font-lock-builtin-face) (122 137 nil)
+     (138 138 font-lock-builtin-face) (139 139 nil)
      (140 142 font-lock-type-face) (143 147 nil)
-     (148 148 font-lock-type-face) (149 149 nil)
+     (148 148 font-lock-builtin-face) (149 149 nil)
      (150 152 font-lock-type-face) (153 158 nil)
      (159 159 font-lock-builtin-face) (160 168 nil)
      (169 173 font-lock-keyword-face) (174 196 nil)
      (197 197 font-lock-builtin-face) (198 203 nil)
-     (204 204 font-lock-type-face) (205 208 nil)
+     (204 204 font-lock-builtin-face) (205 208 nil)
      (209 220 font-lock-type-face) (221 224 nil)
-     (225 226 font-lock-type-face) (227 233 nil)
-     (234 234 font-lock-type-face) (235 243 nil)
-     (244 244 font-lock-type-face) (245 247 nil)
-     (248 248 font-lock-type-face) (249 255 nil)
+     (225 226 font-lock-builtin-face) (227 233 nil)
+     (234 234 font-lock-builtin-face) (235 243 nil)
+     (244 244 font-lock-builtin-face) (245 247 nil)
+     (248 248 font-lock-builtin-face) (249 255 nil)
      (256 263 font-lock-keyword-face) (264 286 nil)
      (287 288 font-lock-builtin-face) (289 289 nil)
      (290 298 font-lock-type-face) (299 300 nil)
      (301 312 font-lock-type-face) (313 316 nil)
      (317 321 font-lock-keyword-face) (322 332 nil)
      (333 344 font-lock-type-face) (345 348 nil)
-     (349 350 font-lock-type-face) (351 360 nil)
+     (349 350 font-lock-builtin-face) (351 360 nil)
      (361 361 font-lock-builtin-face) (362 366 nil)
      (367 378 font-lock-type-face) (379 382 nil)
-     (383 384 font-lock-type-face) (385 388 nil)
+     (383 384 font-lock-builtin-face) (385 388 nil)
      (389 390 font-lock-builtin-face) (391 403 nil)
      (404 409 font-lock-keyword-face) (410 448 nil)
      (449 450 font-lock-builtin-face) (451 451 nil)
@@ -506,5 +506,17 @@ arr = 1 : [2,3]
      (402 402 nil)
      (403 403 font-lock-builtin-face)
      (404 406 nil)
-     (407 407 font-lock-type-face)
+     (407 407 font-lock-builtin-face)
      (408 414 nil))))
+
+(ert-deftest tuple-and-cap-highlighted ()
+  (purescript-test-ranges
+   "myTuple = 1 /\\ (2 ^ 3)"
+   '((1 7 font-lock-function-name-face)
+     (8 8 nil)
+     (9 9 font-lock-builtin-face)
+     (10 12 nil)
+     (13 14 font-lock-builtin-face)
+     (15 18 nil)
+     (19 19 font-lock-builtin-face)
+     (20 23 nil))))