Recognize #line <line-number> <filename> statements in your Guile code.

line-pragma.scm

;; line-pragma.scm
;;
;; This code extends the reader to recognize #l and is meant to
;; be used the same way as the #line pragma in C.  This way you can
;; sprinkle your code with lines like this:
;;
;; (define (f x)
;; #line 314 "increment-literately.w"
;;   (+ x 1))
;;  
;; I wrote it to do literate programming with Guile using nuweb. 
;;
;; Many thanks to dsmith-work, civodul, and others in
;; #guile@irc.freenode.net for their help.
;;
;; Shane Celis

(eval-when (compile load eval)
  (read-hash-extend #\l 
                       (lambda (char port)
                         (let* ((ine (read port))
                                (lineno (read port))
                                (filename (read port)))
                           (if (not (eq? ine 'ine))
                               (error (format #f "Expected '#line <line-number> <filename>'; got '#~a~a ~a \"~a\"'." char ine lineno filename)))
                           (set-port-filename! port filename)
                           (set-port-line! port lineno)
                           (set-port-column! port 0)
                           ""))))