From Newsgroup: comp.lang.lisp

B. Pym wrote:

an `update' function for the mp3 database.
I need a function for doing something like this with a list:

* (xxxx (list :artist "something" :song "sss"))

(:artist :song)

Thanks in advance, and sorry for my bad english.
--
Pablo.

CL-USER> (loop :for (x y) :on (list :artist "something" :song "sss") :by #'cddr
:collect x)
(:ARTIST :SONG)

Gauche Scheme and Racket using unfold from SRFI-1.

(use srfi-1) ;; unfold for Gauche
or
(require srfi/1) ;; unfold for Racket

(unfold null? car cddr '(:artist "something" :song "sss"))
===>
(:artist :song)

Gauche Scheme

(use gauche.lazy) ;; lslices

(map car (lslices '(:artist "something" :song "sss") 2))
===>
(:artist :song)


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