Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!nrl-cmf!ames!pasteur!ucbvax!hplabs!otter!kers
From: kers@otter.HP.COM (Christopher Dollin)
Newsgroups: comp.lang.lisp
Subject: Re: Filtering Vectors in CL Question
Message-ID: <1350003@otter.HP.COM>
Date: 13 Jan 88 15:53:56 GMT
References: <1350001@otter.HP.COM>
Organization: Hewlett-Packard Laboratories,Bristol,UK.
Lines: 15

One note and one direct mail reply (to which I don't have access, being
on a different machine ...) suggested using REMOVE-IF-NOT.

Alas! I have asked the wrong question. The existance of a primitive to
perform the operation gives few clues as to idiomatic style ...

So suppose someone says "please implement 'remove-if-not'. I would like
your solution to generate no garbage if possible and to be reasonably
efficient".

Or suppose they say "write a function to copy a list, eliminating items
that do not satisfy a predicate and duplicating elements which do".

Regards,
Kers.                                | "Why Lisp if you can talk Poperly?"