Re: [Jscheme-user] hack-of-the-day: swing-action

[Ken A. <kan...@bb...>]

At 08:30 PM 8/16/2004 -0400, Geoffrey Knauth wrote:
>while(<>) { print if (/BEGIN/ .. /END/); } 

Perl is hard to beat for one liners.
The best i could come up with was:

(let ((flipFlop (.. (// "BEGIN") (// "END"))))
  (iterate (stdin) (_ (if (flipFlop _) (print _)))))

Here's the rest of the code you'll need:
(load "using/run.scm")

This macro looks a little strange, but i find it very useful for
writing one argument functions.
(define-macro (_ . body) `(lambda (_) ,@body))

(define (stdin) (BufferedReader System.in$))

(define (// pattern) (lambda (x) (.matches x pattern)))

(define (.. p1 p2 . inclusive?)
  (let ((state #f)
        (inclusive? (if (pair? inclusive?) (car inclusive?)
                        #f)))
    (lambda (line)
      (if state (if (p2 line) (begin (set! state #f)
                                     inclusive?)
                    #t)
          (if (p1 line) (begin (set! state #t)
                               inclusive?)
              #f)))))

k