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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: Returning no value
Date: Fri, 30 Aug 2024 09:13:19 -0000 (UTC)
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Ken Tilton wrote:

> Steven M. Haflich wrote:
> > I think the OP may be looking for something like this:
> >
> > cl-user(10): (defun foo()
> >           (let ((x (random 10)))
> >         (and (< 5 x) x)))
> > foo
> > cl-user(11): (loop repeat 10
> >         as x = (foo)
> >         when x collect x)   ; <<<<<
> > (6 8 9)
> 
> Sweet. But not wnat someone already offered?:
> 
>    (loop repeat 10
>          when (foo)
>          collect it)

Gauche Scheme

(define (foo) (let1 x (random-integer 10) (and (< 5 x) x)))

(define (tcollect func tries)
  (if (zero? tries)
    '()
    (append (cond ((func) => list) (#t '()))
            (tcollect func (- tries 1)))))

(tcollect foo 10)

(9 8 9 6 7 9)

(tcollect + 3)

(0 0 0)