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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: (funcall #'or my-list)
Date: Sun, 8 Sep 2024 04:39:11 -0000 (UTC)
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Rob St. Amant wrote:

> I've lately found a use for a function that calls a predicate on each
> element of a list and returns all non-null results.  (I bring this up
> here because it has a SOME-like flavor).
> 
> (defun all-such-that (predicate list &key key)
>   "Return non-nil PREDICATE results for elements in LIST."
>   (loop for elt in list
>      as value = (if key
>                     (funcall predicate (funcall key elt))
>                     (funcall predicate elt))
>      when value
>      collect value))

Gauche Scheme

(define (all-such-that predicate lst :optional (key values))
  (filter-map predicate (map key lst)))

(all-such-that (^n (and (odd? n) n)) '(1 2 3 4 5) square)
  ===>
(1 9 25)

Better:

(define (all-such-that predicate lst :optional (key values))
  (filter-map (^x (and (predicate x) x)) (map key lst)))

(all-such-that odd? '(1 2 3 4 5) square)
  ===>
(1 9 25)