TestTopic1 - Sandbox - s c h e m e w i k i . o r g

Here's some source code formatted by ScmToXexpr (ignore spurious %begin% markup, which comes from the source files being used):

%begin scheme%
(define (for-each-line-in-file filename proc . mode)
  (with-input-from-file
   filename
   (lambda () (apply for-each-line proc (current-input-port) mode))))

(define (for-each-line proc . port+mode)
  (let while ()
    (let ((line (apply read-line port+mode)))
      (unless (eof-object? line)
        (proc line)
        (while)))))

%end%

Here's the same using the BeautifierPlugin :

%begin scheme%
(define (for-each-line-in-file filename proc . mode)
  (with-input-from-file
    filename
    (lambda () (apply for-each-line proc (current-input-port) mode))))

(define (for-each-line proc . port+mode)
  (let while ()
    (let ((line (apply read-line port+mode)))
      (unless (eof-object? line)
        (proc line)
        (while)))))
%end%

Here's an example of the above in action:

%begin scheme%
(for-each-line-in-file
  "ReadingLines.scm"
  (let ((line-num 0))
    (lambda (line) 
      (printf "~a: ~a ~n" line-num line)
      (set! line-num (add1 line-num)))))

%end%

Here's the functional version:

%begin scheme%
(define (fold-lines-in-file filename proc init . mode)
  (with-input-from-file
   filename
   (lambda () (apply fold-lines proc init (current-input-port) mode))))

(define (fold-lines proc init . port+mode)
  (let while ((accum init))
    (let ((line (apply read-line port+mode)))
      (if (eof-object? line) accum
          (while (proc line accum))))))

%end%

Here's an example of the functional version in action:

%begin scheme%
(fold-lines-in-file
  "ReadingLinesWithFold.scm"
  (lambda (line line-num) 
    (printf "~a: ~a ~n" line-num line)
    (add1 line-num)) 
  1)

%end%

-- AntonVanStraaten - 04 Apr 2004