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Sync punctuation to symbol char classes. #541

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Sync punctuation to symbol char classes. #541

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34 changes: 26 additions & 8 deletions haskell-mode.el
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Original file line number Diff line number Diff line change
Expand Up @@ -454,26 +454,44 @@ Run M-x describe-variable haskell-mode-hook for a list of such modes."))
;; Syntax table.
(defvar haskell-mode-syntax-table
(let ((table (make-syntax-table)))

;; Remove default punctuation class because because we try to use
;; punctuation for a purpose of matching Haskell symbol
;; characters. Previous punctuation should get an 'illegal' class,
;; but Emacs does not have one. Lets treat them as whitespace as
;; the next best categorization.
(with-syntax-table table
(dotimes (x 256)
(when (eq (char-syntax x) ?.)
(modify-syntax-entry x "-" table))))

;; Now add punctuation class to characters defined by Haskell
;; report as 'symbol'. Note that ':' is also here as it is also a
;; symbol although not listed among symbols. Ugh, just read
;; Haskell report extra carefuly and you will understand. Notably
;; '-' is not here as it is also a comment character so has to be
;; defined separately.
(mapc (lambda (x)
(modify-syntax-entry x "." table))
"!#$%&*+./:<=>?@^|~")
(modify-syntax-entry ?- ". 123" table)

(modify-syntax-entry ?\ " " table)
(modify-syntax-entry ?\t " " table)
(modify-syntax-entry ?\" "\"" table)
(modify-syntax-entry ?\' "_" table)
(modify-syntax-entry ?_ "_" table)
(modify-syntax-entry ?\( "()" table)
(modify-syntax-entry ?\) ")(" table)
(modify-syntax-entry ?\[ "(]" table)
(modify-syntax-entry ?\] ")[" table)
(modify-syntax-entry ?\[ "(]" table)
(modify-syntax-entry ?\] ")[" table)

(modify-syntax-entry ?\{ "(}1nb" table)
(modify-syntax-entry ?\} "){4nb" table)
(modify-syntax-entry ?- ". 123" table)
(modify-syntax-entry ?\{ "(}1nb" table)
(modify-syntax-entry ?\} "){4nb" table)
(modify-syntax-entry ?\n ">" table)

(modify-syntax-entry ?\` "$`" table)
(modify-syntax-entry ?\\ "\\" table)
(mapc (lambda (x)
(modify-syntax-entry x "." table))
"!#$%&*+./:<=>?@^|~")

;; Haskell symbol characters are treated as punctuation because
;; they are not able to form identifiers with word constituent 'w'
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