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;;; haskell-font-lock.el --- Font locking module for Haskell Mode
;; Copyright 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
;; Copyright 1997-1998 Graeme E Moss, and Tommy Thorn
;; Author: 1997-1998 Graeme E Moss <gem@cs.york.ac.uk>
;; 1997-1998 Tommy Thorn <thorn@irisa.fr>
;; 2003 Dave Love <fx@gnu.org>
;; Keywords: faces files Haskell
;; This file is not part of GNU Emacs.
;; This file is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 3, or (at your option)
;; any later version.
;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;; Purpose:
;;
;; To support fontification of standard Haskell keywords, symbols,
;; functions, etc. Supports full Haskell 1.4 as well as LaTeX- and
;; Bird-style literate scripts.
;;
;; Installation:
;;
;; To turn font locking on for all Haskell buffers under the Haskell
;; mode of Moss&Thorn, add this to .emacs:
;;
;; (add-hook 'haskell-mode-hook 'turn-on-haskell-font-lock)
;;
;; Otherwise, call `turn-on-haskell-font-lock'.
;;
;;
;; Customisation:
;;
;; The colours and level of font locking may be customised. See the
;; documentation on `turn-on-haskell-font-lock' for more details.
;;
;; Present Limitations/Future Work (contributions are most welcome!):
;;
;; . Debatable whether `()' `[]' `(->)' `(,)' `(,,)' etc. should be
;; highlighted as constructors or not. Should the `->' in
;; `id :: a -> a' be considered a constructor or a keyword? If so,
;; how do we distinguish this from `\x -> x'? What about the `\'?
;;
;; . XEmacs can support both `--' comments and `{- -}' comments
;; simultaneously. If XEmacs is detected, this should be used.
;;
;; . Support for GreenCard?
;;
;;
;; All functions/variables start with
;; `(turn-(on/off)-)haskell-font-lock' or `haskell-fl-'.
;;; Change Log:
;; Version 1.3:
;; From Dave Love:
;; Support for proper behaviour (including with Unicode identifiers)
;; in Emacs 21 only hacked in messily to avoid disturbing the old
;; stuff. Needs integrating more cleanly. Allow literate comment
;; face to be customized. Some support for fontifying definitions.
;; (I'm not convinced the faces should be customizable -- fontlock
;; faces are normally expected to be consistent.)
;;
;; Version 1.2:
;; Added support for LaTeX-style literate scripts. Allow whitespace
;; after backslash to end a line for string continuations.
;;
;; Version 1.1:
;; Use own syntax table. Use backquote (neater). Stop ''' being
;; highlighted as quoted character. Fixed `\"' fontification bug
;; in comments.
;;
;; Version 1.0:
;; Brought over from Haskell mode v1.1.
;;; Code:
(require 'haskell-mode)
(require 'font-lock)
(with-no-warnings (require 'cl))
(defcustom haskell-font-lock-symbols nil
"Display \\ and -> and such using symbols in fonts.
This may sound like a neat trick, but be extra careful: it changes the
alignment and can thus lead to nasty surprises w.r.t layout.
If t, try to use whichever font is available. Otherwise you can
set it to a particular font of your preference among `japanese-jisx0208'
and `unicode'."
:group 'haskell
:type '(choice (const nil)
(const t)
(const unicode)
(const japanese-jisx0208)))
(defconst haskell-font-lock-symbols-alist
(append
;; Prefer single-width Unicode font for lambda.
(and (fboundp 'decode-char)
(memq haskell-font-lock-symbols '(t unicode))
(list (cons "\\" (decode-char 'ucs 955))))
;; The symbols can come from a JIS0208 font.
(and (fboundp 'make-char) (fboundp 'charsetp) (charsetp 'japanese-jisx0208)
(memq haskell-font-lock-symbols '(t japanese-jisx0208))
(list (cons "not" (make-char 'japanese-jisx0208 34 76))
(cons "\\" (make-char 'japanese-jisx0208 38 75))
(cons "->" (make-char 'japanese-jisx0208 34 42))
(cons "<-" (make-char 'japanese-jisx0208 34 43))
(cons "=>" (make-char 'japanese-jisx0208 34 77))
;; FIXME: I'd like to either use ∀ or ∃ depending on how the
;; `forall' keyword is used, but currently the rest of the
;; code assumes that such ambiguity doesn't happen :-(
(cons "forall" (make-char 'japanese-jisx0208 34 79))))
;; Or a unicode font.
(and (fboundp 'decode-char)
(memq haskell-font-lock-symbols '(t unicode))
(list (cons "not" (decode-char 'ucs 172))
(cons "->" (decode-char 'ucs 8594))
(cons "<-" (decode-char 'ucs 8592))
(cons "=>" (decode-char 'ucs 8658))
(cons "()" (decode-char 'ucs #X2205))
(cons "==" (decode-char 'ucs #X2261))
(cons "/=" (decode-char 'ucs #X2262))
(cons ">=" (decode-char 'ucs #X2265))
(cons "<=" (decode-char 'ucs #X2264))
(cons "!!" (decode-char 'ucs #X203C))
(cons "&&" (decode-char 'ucs #X2227))
(cons "||" (decode-char 'ucs #X2228))
(cons "sqrt" (decode-char 'ucs #X221A))
(cons "undefined" (decode-char 'ucs #X22A5))
(cons "pi" (decode-char 'ucs #X3C0))
(cons "~>" (decode-char 'ucs 8669)) ;; Omega language
;; (cons "~>" (decode-char 'ucs 8605)) ;; less desirable
(cons "-<" (decode-char 'ucs 8610)) ;; Paterson's arrow syntax
;; (cons "-<" (decode-char 'ucs 10521)) ;; nicer but uncommon
(cons "::" (decode-char 'ucs 8759))
(list "." (decode-char 'ucs 8728) ; (decode-char 'ucs 9675)
;; Need a predicate here to distinguish the . used by
;; forall <foo> . <bar>.
'haskell-font-lock-dot-is-not-composition)
(cons "forall" (decode-char 'ucs 8704)))))
"Alist mapping Haskell symbols to chars.
Each element has the form (STRING . CHAR) or (STRING CHAR PREDICATE).
STRING is the Haskell symbol.
CHAR is the character with which to represent this symbol.
PREDICATE if present is a function of one argument (the start position
of the symbol) which should return non-nil if this mapping should be disabled
at that position.")
(defun haskell-font-lock-dot-is-not-composition (start)
"Return non-nil if the \".\" at START is not a composition operator.
This is the case if the \".\" is part of a \"forall <tvar> . <type>\"."
(save-excursion
(goto-char start)
(re-search-backward "\\<forall\\>[^.\"]*\\="
(line-beginning-position) t)))
;; Use new vars for the font-lock faces. The indirection allows people to
;; use different faces than in other modes, as before.
(defvar haskell-keyword-face 'font-lock-keyword-face)
(defvar haskell-constructor-face 'font-lock-type-face)
;; This used to be `font-lock-variable-name-face' but it doesn't result in
;; a highlighting that's consistent with other modes (it's mostly used
;; for function defintions).
(defvar haskell-definition-face 'font-lock-function-name-face)
;; This is probably just wrong, but it used to use
;; `font-lock-function-name-face' with a result that was not consistent with
;; other major modes, so I just exchanged with `haskell-definition-face'.
(defvar haskell-operator-face 'font-lock-variable-name-face)
(defvar haskell-default-face nil)
(defvar haskell-literate-comment-face 'font-lock-doc-face
"Face with which to fontify literate comments.
Set to `default' to avoid fontification of them.")
(defconst haskell-emacs21-features (string-match "[[:alpha:]]" "x")
"Non-nil if we have regexp char classes.
Assume this means we have other useful features from Emacs 21.")
(defun haskell-font-lock-compose-symbol (alist)
"Compose a sequence of ascii chars into a symbol.
Regexp match data 0 points to the chars."
;; Check that the chars should really be composed into a symbol.
(let* ((start (match-beginning 0))
(end (match-end 0))
(syntaxes (cond
((eq (char-syntax (char-after start)) ?w) '(?w))
;; Special case for the . used for qualified names.
((and (eq (char-after start) ?\.) (= end (1+ start)))
'(?_ ?\\ ?w))
(t '(?_ ?\\))))
sym-data)
(if (or (memq (char-syntax (or (char-before start) ?\ )) syntaxes)
(memq (char-syntax (or (char-after end) ?\ )) syntaxes)
(memq (get-text-property start 'face)
'(font-lock-doc-face font-lock-string-face
font-lock-comment-face))
(and (consp (setq sym-data (cdr (assoc (match-string 0) alist))))
(let ((pred (cadr sym-data)))
(setq sym-data (car sym-data))
(funcall pred start))))
;; No composition for you. Let's actually remove any composition
;; we may have added earlier and which is now incorrect.
(remove-text-properties start end '(composition))
;; That's a symbol alright, so add the composition.
(compose-region start end sym-data)))
;; Return nil because we're not adding any face property.
nil)
(defun haskell-font-lock-symbols-keywords ()
(when (fboundp 'compose-region)
(let ((alist nil))
(dolist (x haskell-font-lock-symbols-alist)
(when (and (if (fboundp 'char-displayable-p)
(char-displayable-p (if (consp (cdr x)) (cadr x) (cdr x)))
(if (fboundp 'latin1-char-displayable-p)
(latin1-char-displayable-p (if (consp (cdr x))
(cadr x)
(cdr x)))
t))
(not (assoc (car x) alist))) ; Not yet in alist.
(push x alist)))
(when alist
`((,(regexp-opt (mapcar 'car alist) t)
(0 (haskell-font-lock-compose-symbol ',alist)
;; In Emacs-21, if the `override' field is nil, the face
;; expressions is only evaluated if the text has currently
;; no face. So force evaluation by using `keep'.
keep)))))))
;; The font lock regular expressions.
(defun haskell-font-lock-keywords-create (literate)
"Create fontification definitions for Haskell scripts.
Returns keywords suitable for `font-lock-keywords'."
(let* (;; Bird-style literate scripts start a line of code with
;; "^>", otherwise a line of code starts with "^".
(line-prefix (if (eq literate 'bird) "^> ?" "^"))
;; Most names are borrowed from the lexical syntax of the Haskell
;; report.
;; Some of these definitions have been superseded by using the
;; syntax table instead.
;; (ASCsymbol "-!#$%&*+./<=>?@\\\\^|~")
;; Put the minus first to make it work in ranges.
;; We allow _ as the first char to fit GHC
(varid "\\b[[:lower:]_][[:alnum:]'_]*\\b")
;; We allow ' preceding conids because of DataKinds/PolyKinds
(conid "\\b'?[[:upper:]][[:alnum:]'_]*\\b")
(modid (concat "\\b" conid "\\(\\." conid "\\)*\\b"))
(qvarid (concat modid "\\." varid))
(qconid (concat modid "\\." conid))
(sym
;; We used to use the below for non-Emacs21, but I think the
;; regexp based on syntax works for other emacsen as well. -- Stef
;; (concat "[" symbol ":]+")
;; Add backslash to the symbol-syntax chars. This seems to
;; be thrown for some reason by backslash's escape syntax.
"\\(\\s_\\|\\\\\\)+")
;; Reserved operations
(reservedsym
(concat "\\S_"
;; (regexp-opt '(".." "::" "=" "\\" "|" "<-" "->"
;; "@" "~" "=>") t)
"\\(->\\|\\.\\.\\|::\\|∷\\|<-\\|=>\\|[=@\\|~]\\)"
"\\S_"))
;; Reserved identifiers
(reservedid
(concat "\\<"
;; `as', `hiding', and `qualified' are part of the import
;; spec syntax, but they are not reserved.
;; `_' can go in here since it has temporary word syntax.
;; (regexp-opt
;; '("case" "class" "data" "default" "deriving" "do"
;; "else" "if" "import" "in" "infix" "infixl"
;; "infixr" "instance" "let" "module" "newtype" "of"
;; "then" "type" "where" "_") t)
"\\(_\\|c\\(ase\\|lass\\)\\|d\\(ata\\|e\\(fault\\|riving\\)\\|o\\)\\|else\\|i\\(mport\\|n\\(fix[lr]?\\|stance\\)\\|[fn]\\)\\|let\\|module\\|mdo\\|newtype\\|of\\|rec\\|proc\\|t\\(hen\\|ype\\)\\|where\\)"
"\\>"))
;; This unreadable regexp matches strings and character
;; constants. We need to do this with one regexp to handle
;; stuff like '"':"'". The regexp is the composition of
;; "([^"\\]|\\.)*" for strings and '([^\\]|\\.[^']*)' for
;; characters, allowing for string continuations.
;; Could probably be improved...
(string-and-char
(concat "\\(\\(\"\\|" line-prefix "[ \t]*\\\\\\)\\([^\"\\\\\n]\\|\\\\.\\)*\\(\"\\|\\\\[ \t]*$\\)\\|'\\([^'\\\\\n]\\|\\\\.[^'\n]*\\)'\\)"))
;; Top-level declarations
(topdecl-var
(concat line-prefix "\\(" varid "\\)\\s-*"
;; optionally allow for a single newline after identifier
;; NOTE: not supported for bird-style .lhs files
(if (eq literate 'bird) nil "\\([\n]\\s-+\\)?")
;; A toplevel declaration can be followed by a definition
;; (=), a type (::) or (∷), a guard, or a pattern which can
;; either be a variable, a constructor, a parenthesized
;; thingy, or an integer or a string.
"\\(" varid "\\|" conid "\\|::\\|∷\\|=\\||\\|\\s(\\|[0-9\"']\\)"))
(topdecl-var2
(concat line-prefix "\\(" varid "\\|" conid "\\)\\s-*`\\(" varid "\\)`"))
(topdecl-sym
(concat line-prefix "\\(" varid "\\|" conid "\\)\\s-*\\(" sym "\\)"))
(topdecl-sym2 (concat line-prefix "(\\(" sym "\\))"))
keywords)
(setq keywords
`(;; NOTICE the ordering below is significant
;;
("^<<<<<<< .*$" 0 'font-lock-warning-face t)
("^=======" 0 'font-lock-warning-face t)
("^>>>>>>> .*$" 0 'font-lock-warning-face t)
("^#.*$" 0 'font-lock-preprocessor-face t)
,@(unless haskell-emacs21-features ;Supports nested comments?
;; Expensive.
`((,string-and-char 1 font-lock-string-face)))
;; This was originally at the very end (and needs to be after
;; all the comment/string/doc highlighting) but it seemed to
;; trigger a bug in Emacs-21.3 which caused the compositions to
;; be "randomly" dropped. Moving it earlier seemed to reduce
;; the occurrence of the bug.
,@(haskell-font-lock-symbols-keywords)
(,reservedid 1 (symbol-value 'haskell-keyword-face))
(,reservedsym 1 (symbol-value 'haskell-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\\>\\)?"
(1 (symbol-value 'haskell-keyword-face) nil lax)
(2 (symbol-value 'haskell-keyword-face) nil lax)
(3 (symbol-value 'haskell-keyword-face) nil lax)
(4 (symbol-value 'haskell-keyword-face) nil lax))
(,reservedsym 1 (symbol-value 'haskell-operator-face))
;; Special case for `foreign import'
;; keywords in foreign import statements but are not otherwise reserved.
("\\<\\(foreign\\)[ \t]+\\(import\\)[ \t]+\\(?:\\(ccall\\|stdcall\\|cplusplus\\|jvm\\|dotnet\\)[ \t]+\\)?\\(?:\\(safe\\|unsafe\\|interruptible\\)[ \t]+\\)?"
(1 (symbol-value 'haskell-keyword-face) nil lax)
(2 (symbol-value 'haskell-keyword-face) nil lax)
(3 (symbol-value 'haskell-keyword-face) nil lax)
(4 (symbol-value 'haskell-keyword-face) nil lax))
(,reservedsym 1 (symbol-value 'haskell-operator-face))
;; Special case for `foreign export'
;; keywords in foreign export statements but are not otherwise reserved.
("\\<\\(foreign\\)[ \t]+\\(export\\)[ \t]+\\(?:\\(ccall\\|stdcall\\|cplusplus\\|jvm\\|dotnet\\)[ \t]+\\)?"
(1 (symbol-value 'haskell-keyword-face) nil lax)
(2 (symbol-value 'haskell-keyword-face) nil lax)
(3 (symbol-value 'haskell-keyword-face) nil lax))
;; Toplevel Declarations.
;; Place them *before* generic id-and-op highlighting.
(,topdecl-var (1 (symbol-value 'haskell-definition-face)))
(,topdecl-var2 (2 (symbol-value 'haskell-definition-face)))
(,topdecl-sym (2 (symbol-value 'haskell-definition-face)))
(,topdecl-sym2 (1 (symbol-value 'haskell-definition-face)))
;; These four are debatable...
("(\\(,*\\|->\\))" 0 (symbol-value 'haskell-constructor-face))
("\\[\\]" 0 (symbol-value 'haskell-constructor-face))
;; Expensive.
(,qvarid 0 (symbol-value 'haskell-default-face))
(,qconid 0 (symbol-value 'haskell-constructor-face))
(,(concat "\`" varid "\`") 0 (symbol-value 'haskell-operator-face))
;; Expensive.
(,conid 0 (symbol-value 'haskell-constructor-face))
;; Very expensive.
(,sym 0 (if (eq (char-after (match-beginning 0)) ?:)
haskell-constructor-face
haskell-operator-face))))
(unless (boundp 'font-lock-syntactic-keywords)
(case literate
(bird
(setq keywords
`(("^[^>\n].*$" 0 haskell-comment-face t)
,@keywords
("^>" 0 haskell-default-face t))))
((latex tex)
(setq keywords
`((haskell-fl-latex-comments 0 'font-lock-comment-face t)
,@keywords)))))
keywords))
;; The next three aren't used in Emacs 21.
(defvar haskell-fl-latex-cache-pos nil
"Position of cache point used by `haskell-fl-latex-cache-in-comment'.
Should be at the start of a line.")
(defvar haskell-fl-latex-cache-in-comment nil
"If `haskell-fl-latex-cache-pos' is outside a
\\begin{code}..\\end{code} block (and therefore inside a comment),
this variable is set to t, otherwise nil.")
(defun haskell-fl-latex-comments (end)
"Sets `match-data' according to the region of the buffer before end
that should be commented under LaTeX-style literate scripts."
(let ((start (point)))
(if (= start end)
;; We're at the end. No more to fontify.
nil
(if (not (eq start haskell-fl-latex-cache-pos))
;; If the start position is not cached, calculate the state
;; of the start.
(progn
(setq haskell-fl-latex-cache-pos start)
;; If the previous \begin{code} or \end{code} is a
;; \begin{code}, then start is not in a comment, otherwise
;; it is in a comment.
(setq haskell-fl-latex-cache-in-comment
(if (and
(re-search-backward
"^\\(\\(\\\\begin{code}\\)\\|\\(\\\\end{code}\\)\\)$"
(point-min) t)
(match-end 2))
nil t))
;; Restore position.
(goto-char start)))
(if haskell-fl-latex-cache-in-comment
(progn
;; If start is inside a comment, search for next \begin{code}.
(re-search-forward "^\\\\begin{code}$" end 'move)
;; Mark start to end of \begin{code} (if present, till end
;; otherwise), as a comment.
(set-match-data (list start (point)))
;; Return point, as a normal regexp would.
(point))
;; If start is inside a code block, search for next \end{code}.
(if (re-search-forward "^\\\\end{code}$" end t)
;; If one found, mark it as a comment, otherwise finish.
(point))))))
(defconst haskell-basic-syntactic-keywords
'(;; Character constants (since apostrophe can't have string syntax).
;; Beware: do not match something like 's-}' or '\n"+' since the first '
;; might be inside a comment or a string.
;; This still gets fooled with "'"'"'"'"'"', but ... oh well.
("\\Sw\\('\\)\\([^\\'\n]\\|\\\\.[^\\'\n \"}]*\\)\\('\\)" (1 "|") (3 "|"))
;; The \ is not escaping in \(x,y) -> x + y.
("\\(\\\\\\)(" (1 "."))
;; The second \ in a gap does not quote the subsequent char.
;; It's probably not worth the trouble, tho.
;; ("^[ \t]*\\(\\\\\\)" (1 "."))
;; Deal with instances of `--' which don't form a comment
("\\s_\\{3,\\}" (0 (cond ((numberp (nth 4 (syntax-ppss)))
;; There are no such instances inside nestable comments
nil)
((string-match "\\`-*\\'" (match-string 0))
;; Sequence of hyphens. Do nothing in
;; case of things like `{---'.
nil)
(t "_")))) ; other symbol sequence
))
(defconst haskell-bird-syntactic-keywords
(cons '("^[^\n>]" (0 "<"))
haskell-basic-syntactic-keywords))
(defconst haskell-latex-syntactic-keywords
(append
'(("^\\\\begin{code}\\(\n\\)" 1 "!")
;; Note: buffer is widened during font-locking.
("\\`\\(.\\|\n\\)" (1 "!")) ; start comment at buffer start
("^\\(\\\\\\)end{code}$" 1 "!"))
haskell-basic-syntactic-keywords))
(defcustom haskell-font-lock-haddock (boundp 'font-lock-doc-face)
"If non-nil try to highlight Haddock comments specially."
:type 'boolean
:group 'haskell)
(defvar haskell-font-lock-seen-haddock nil)
(make-variable-buffer-local 'haskell-font-lock-seen-haddock)
(defun haskell-syntactic-face-function (state)
"`font-lock-syntactic-face-function' for Haskell."
(cond
((nth 3 state) font-lock-string-face) ; as normal
;; Else comment. If it's from syntax table, use default face.
((or (eq 'syntax-table (nth 7 state))
(and (eq haskell-literate 'bird)
(memq (char-before (nth 8 state)) '(nil ?\n))))
haskell-literate-comment-face)
;; Try and recognize Haddock comments. From what I gather from its
;; documentation, its comments can take the following forms:
;; a) {-| ... -}
;; b) {-^ ... -}
;; c) -- | ...
;; d) -- ^ ...
;; e) -- ...
;; Where `e' is the tricky one: it is only a Haddock comment if it
;; follows immediately another Haddock comment. Even an empty line
;; breaks such a sequence of Haddock comments. It is not clear if `e'
;; can follow any other case, so I interpreted it as following only cases
;; c,d,e (not a or b). In any case, this `e' is expensive since it
;; requires extra work for each and every non-Haddock comment, so I only
;; go through the more expensive check if we've already seen a Haddock
;; comment in the buffer.
((and haskell-font-lock-haddock
(save-excursion
(goto-char (nth 8 state))
(or (looking-at "\\(-- \\|{-\\)[ \\t]*[|^]")
(and haskell-font-lock-seen-haddock
(looking-at "-- ")
(let ((doc nil)
pos)
(while (and (not doc)
(setq pos (line-beginning-position))
(forward-comment -1)
(eq (line-beginning-position 2) pos)
(looking-at "--\\( [|^]\\)?"))
(setq doc (match-beginning 1)))
doc)))))
(set (make-local-variable 'haskell-font-lock-seen-haddock) t)
font-lock-doc-face)
(t font-lock-comment-face)))
(defconst haskell-font-lock-keywords
(haskell-font-lock-keywords-create nil)
"Font lock definitions for non-literate Haskell.")
(defconst haskell-font-lock-bird-literate-keywords
(haskell-font-lock-keywords-create 'bird)
"Font lock definitions for Bird-style literate Haskell.")
(defconst haskell-font-lock-latex-literate-keywords
(haskell-font-lock-keywords-create 'latex)
"Font lock definitions for LaTeX-style literate Haskell.")
;;;###autoload
(defun haskell-font-lock-choose-keywords ()
(let ((literate (if (boundp 'haskell-literate) haskell-literate)))
(case literate
(bird haskell-font-lock-bird-literate-keywords)
((latex tex) haskell-font-lock-latex-literate-keywords)
(t haskell-font-lock-keywords))))
(defun haskell-font-lock-choose-syntactic-keywords ()
(let ((literate (if (boundp 'haskell-literate) haskell-literate)))
(case literate
(bird haskell-bird-syntactic-keywords)
((latex tex) haskell-latex-syntactic-keywords)
(t haskell-basic-syntactic-keywords))))
(defun haskell-font-lock-defaults-create ()
"Locally set `font-lock-defaults' for Haskell."
(set (make-local-variable 'font-lock-defaults)
'(haskell-font-lock-choose-keywords
nil nil ((?\' . "w") (?_ . "w")) nil
(font-lock-syntactic-keywords
. haskell-font-lock-choose-syntactic-keywords)
(font-lock-syntactic-face-function
. haskell-syntactic-face-function)
;; Get help from font-lock-syntactic-keywords.
(parse-sexp-lookup-properties . t))))
;; The main functions.
(defun turn-on-haskell-font-lock ()
"Turns on font locking in current buffer for Haskell 1.4 scripts.
Changes the current buffer's `font-lock-defaults', and adds the
following variables:
`haskell-keyword-face' for reserved keywords and syntax,
`haskell-constructor-face' for data- and type-constructors, class names,
and module names,
`haskell-operator-face' for symbolic and alphanumeric operators,
`haskell-default-face' for ordinary code.
The variables are initialised to the following font lock default faces:
`haskell-keyword-face' `font-lock-keyword-face'
`haskell-constructor-face' `font-lock-type-face'
`haskell-operator-face' `font-lock-function-name-face'
`haskell-default-face' <default face>
Two levels of fontification are defined: level one (the default)
and level two (more colour). The former does not colour operators.
Use the variable `font-lock-maximum-decoration' to choose
non-default levels of fontification. For example, adding this to
.emacs:
(setq font-lock-maximum-decoration '((haskell-mode . 2) (t . 0)))
uses level two fontification for `haskell-mode' and default level for
all other modes. See documentation on this variable for further
details.
To alter an attribute of a face, add a hook. For example, to change
the foreground colour of comments to brown, add the following line to
.emacs:
(add-hook 'haskell-font-lock-hook
(lambda ()
(set-face-foreground 'haskell-comment-face \"brown\")))
Note that the colours available vary from system to system. To see
what colours are available on your system, call
`list-colors-display' from emacs.
To turn font locking on for all Haskell buffers, add this to .emacs:
(add-hook 'haskell-mode-hook 'turn-on-haskell-font-lock)
To turn font locking on for the current buffer, call
`turn-on-haskell-font-lock'. To turn font locking off in the current
buffer, call `turn-off-haskell-font-lock'.
Bird-style literate Haskell scripts are supported: If the value of
`haskell-literate-bird-style' (automatically set by the Haskell mode
of Moss&Thorn) is non-nil, a Bird-style literate script is assumed.
Invokes `haskell-font-lock-hook' if not nil."
(haskell-font-lock-defaults-create)
(run-hooks 'haskell-font-lock-hook)
(turn-on-font-lock))
(defun turn-off-haskell-font-lock ()
"Turns off font locking in current buffer."
(font-lock-mode -1))
;; Provide ourselves:
(provide 'haskell-font-lock)
;; Local Variables:
;; byte-compile-warnings: (not cl-functions)
;; tab-width: 8
;; End:
;;; haskell-font-lock.el ends here
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