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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.lisp
Subject: Re: Loop? ptooey
Date: Sun, 6 Jul 2025 12:31:06 -0000 (UTC)
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B. Pym wrote:

> > Kenny Tilton wrote:
> > 
> > > > KMP: The example you cite is quite simplistic.....snip...A
> > > > loop like this: 
> > > > 
> > > >            (loop for x from 0 
> > > >                  for y in some-list 
> > > >                  when (good-result? y) 
> > > >                    collect (list x y)) 
> > > > 
> > > > is easy to write and maintain, and much easier to explain than the
> > > > equivalent, but more Lispy:
> > > > 
> > > >            (do ((x 0 (+ x 1)) 
> > > >                 (y-list some-list (cdr y-list)) 
> > > >            (result '())) 
> > > >               ((null y-list) ;; [fixed] 
> > > >                 (nreverse result)) 
> > > >            (let ((y (first y-list))) 
> > > >               (when (good-result? y) 
> > > >                 (push (list x y) result)))) 
> > > 
> > > Ugh. Howse about: 
> > > 
> > > (let ((goody-pos -1) 
> > >        goodies) 
> > >     (dolist (it some-list (nreverse goodies)) 
> > >       (incf goody-pos) 
> > >       (when (good-result? it) 
> > >         (push (list goody-pos it) goodies)))) 
> > > 
> > > perhaps i will be swayed someday by the charms of loop, but i gotta
> > > tell you, i just don't get it. is loop for people who can't read lisp?
> > > can't be, lisp is easier to read than loop. stumped.
> 
> Gauche Scheme:
> 
> (use gauche.collection)   ;; size-of
> 
> (filter-map
>   (lambda (x i)
>     (and  (> (size-of x) 1)  (list i x)))
>   '("a" "or" "I" "can" "o" "burn")
>   (liota))
> 
>   ===>
> ((1 "or") (3 "can") (5 "burn"))

(use srfi-42) ;; list-ec

(define some-list '((d) () (g) (o) () (w)))

(list-ec
  (:list x (index i) some-list)
  (if (pair? x))
  (list i x))

  ===>
((0 (d)) (2 (g)) (3 (o)) (5 (w)))