Daniel Bastos <dbastos+0### [at] toledocom> wrote:
> #!/usr/bin/env mzscheme
> (module cat scheme/base
>
> (define (interact f)
>   (let ([ln (read-line)])
>      (cond
>       [(not (eq? ln eof))
>          (and
>     (printf "~a\n" (f ln))
>     (interact f))])))
>
> (define (id x) x)
>
> (define (cat files)
>   (for-each
>    (lambda (x)
>      (with-input-from-file x
>        (lambda ()
>   (interact id))))
>    files))
>
> ;main
> (cat (vector->list (current-command-line-arguments)))
> )
>
> With with-input-from-file, we get the stdin connected to the file
> opened, so no changes in interact were required.

That's the PLT way.  here's another:

#!r6rs
(import (rnrs base)(rnrs io simple)(rnrs programs))

; simple and straightforward standard R6RS scheme solution
(define (cat files)
  (for-each
    (lambda (file)
      (call-with-input-file file
        (lambda (port)
          ; no simple line-oriented IO in standard R6RS
          ; so you either write one or loop char-by-char
          (let go ((c (read-char port)))
            (if (not (eof-object? c))
              (begin
                (write-char c)
                (go (read-char port))))))))
    files))

(cat (cdr (command-line)))


you can run it like:

plt-r6rs cat.scm foo.txt bar.txt

> This cat does not handle exceptions. I might see how that works next.

Neither does mine.  There is a file-exists? function though:
http://www.r6rs.org/final/html/r6rs-lib/r6rs-lib-Z-H-10.html#node_chap_9

> Lisp likes might be hackestables.

I just love Lisp, Scheme in particular.  Minimalist like C, only much higher
level.  Incidentally, the only two languages I truly enjoy, for different
purposes sure.

yes, I'm aware the C solution for this particular example would be way
shorter... :P

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