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  • Re: Loop? ptooey

    From B. Pym@Nobody447095@here-nor-there.org to comp.lang.lisp on Sun Jul 6 12:31:06 2025
    From Newsgroup: comp.lang.lisp

    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)))

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