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+;;; guile-syntax-highlight --- General-purpose syntax highlighter
+;;; Copyright © 2015 David Thompson <davet@gnu.org>
+;;;
+;;; Guile-syntax-highlight is free software; you can redistribute it
+;;; and/or modify it under the terms of the GNU Lesser General Public
+;;; License as published by the Free Software Foundation; either
+;;; version 3 of the License, or (at your option) any later version.
+;;;
+;;; Guile-syntax-highlight 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 Lesser General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Lesser General Public
+;;; License along with guile-syntax-highlight.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; Syntax highlighting for Scheme.
+;;
+;;; Code:
+
+(define-module (syntax-highlight scheme)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-41)
+  #:use-module (syntax-highlight parsers)
+  #:export (scheme-highlighter))
+
+(define char-set:lisp-delimiters
+  (char-set-union char-set:whitespace
+                  (char-set #\( #\) #\[ #\] #\{ #\})))
+
+(define (lisp-delimiter? char)
+  (char-set-contains? char-set:lisp-delimiters char))
+
+(define (parse-specials special-words)
+  "Create a parser for SPECIAL-WORDS, a list of important terms for a
+language."
+  (define (special word)
+    (let ((parser (tagged-parser 'special (parse-string word))))
+      (lambda (stream)
+        (let-values (((result rest-of-stream) (parser stream)))
+          (if (and result (lisp-delimiter? (stream-car stream)))
+              (values result rest-of-stream)
+              (parse-fail stream))))))
+
+  (fold parse-either parse-never (map special special-words)))
+
+(define (parse-openers openers)
+  (define (open opener)
+    (tagged-parser 'open (parse-string opener)))
+
+  (fold parse-either parse-never (map open openers)))
+
+(define (parse-closers closers)
+  (define (close closer)
+    (tagged-parser 'close (parse-string closer)))
+
+  (fold parse-either parse-never (map close closers)))
+
+(define parse-symbol
+  (tagged-parser 'symbol
+                 (parse-char-set
+                  (char-set-complement char-set:lisp-delimiters))))
+
+(define parse-keyword
+  (tagged-parser 'keyword
+                 (parse-map string-concatenate
+                            (parse-each (parse-string "#:")
+                                        (parse-char-set
+                                         (char-set-complement
+                                          char-set:lisp-delimiters))))))
+
+(define parse-string-literal
+  (tagged-parser 'string (parse-delimited "\"")))
+
+(define parse-comment
+  (tagged-parser 'comment (parse-delimited ";" #:until "\n")))
+
+(define parse-quoted-symbol
+  (tagged-parser 'symbol (parse-delimited "#{" #:until "}#")))
+
+(define scheme-highlighter
+  (parse-many
+   (parse-any parse-whitespace
+              (parse-openers '("(" "[" "{"))
+              (parse-closers '(")" "]" "}"))
+              (parse-specials '("define" "lambda"))
+              parse-string-literal
+              parse-comment
+              parse-keyword
+              parse-quoted-symbol
+              parse-symbol)))
+
+;; (scheme-highlighter
+;;  (string->stream
+;;   "(define* (foo bar #:key (baz 'quux))
+;;   \"This is a docstring!\"
+;;   #u8(1 2 3)
+;;   (1+ bar))"))