RetroBBS - comp.lang.lisp - .Re: Map, Filter, and Reduce in Lisp

.Re: Map, Filter, and Reduce in Lisp

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https://www.rocksolidbbs.com/devel/article-flat.php?id=16998&group=comp.lang.lisp#16998

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From: No_spamming@noWhere_7073.org (Robert L.)
Newsgroups: comp.lang.lisp
Subject: .Re: Map, Filter, and Reduce in Lisp
Date: Sat, 26 Mar 2022 21:32:49 -0000 (UTC)
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by: Robert L. - Sat, 26 Mar 2022 21:32 UTC

Vassil Nikolov wrote:

> | I'm familiar with map/filter/reduce from other languages. But I can't
> | find a simple doc on how to do these in Lisp! What I find perplexing
> | is that I thought that Lisp invented this paradigm?
>
> | What is the simplest way of map / filter / reducing a collection
> | (perhaps a list) in Lisp?
>
> I don't have a reference ready, but note that filtering in Common
> Lisp can be done with REMOVE, REMOVE-IF, and REMOVE-IF-NOT; here is a
> trivial example (one of many possible):
>
> (reduce #'+ (map 'list #'round (remove-if #'symbolp '(foo 1.2 bar 3.4
> baz 5.6))))
> => 10

Instead of CL, let's use a Lisp.

Gauche Scheme:

(fold + 0 (map round (remove symbol? '(foo 1.2 bar 3.4 baz 5.6))))

===>
10.0

Earth is a beta site.

devel / comp.lang.lisp / .Re: Map, Filter, and Reduce in Lisp

Subject	Author
.Re: Map, Filter, and Reduce in Lisp	Robert L.