(defvar *chunkhash* nil "this hash table contains the chunks found")
(defvar *chunknoise* nil "turn this on to debug internals")

(defun tangle (filename topchunk &optional file)
 "Extract the source code from a pamphlet file"
 (let ((noweb? (char= (schar topchunk 0) #\<)))
  (setq *chunkhash* (make-hash-table :test #'equal))
  (when *chunknoise* (format t "PASS 1~%"))
  (gcl-hashchunks (gcl-read-file filename) noweb?)
  (when *chunknoise* (format t "PASS 2~%"))
  (if (and file (stringp file))
   (with-open-file (out file :direction :output)
     (gcl-expand topchunk noweb? out))
   (gcl-expand topchunk noweb? t)))
  (values))