Re: getting list of keys

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)