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comp.lang.lisp

Re: I still don't get MAPCAN

William James

11/4/2015 11:41:00 PM

Ken Tilton wrote:

> > MAPCAN is terribly useful when you want to collect only some things:
> >
> > (defun find-interesting (huge-list)
> > (mapcan #'(lambda (e) (if (interestingp e) (list e) nil)) huge-list))
>
> ick.
>
> (loop for e in huge-list when (interestingp e) collect e)

Gauche Scheme:

(filter interesting? huge-list)

Only a dung-beetle (a worshipper of CL) would prefer Kenny's version.

MatzLisp (Ruby):

huge_array.select(&:interesting?)

or

huge_array.select{|x| interesting?(x)}

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