Re: quickly find all executables

[Kevin Rodgers]

Kin Cho wrote:

> Eric Marsden <emarsden@laas.fr> writes:
>
> >  (remove-if-not 'file-executable-p
> >     (mapcan (lambda (dir) (directory-files dir t))
> >             (remove-if-not 'file-directory-p exec-path)))
>
> Thanks.  This code is significantly shorter than Kevin Rodgers'
> version, and it runs in virtually the same amount of time for my
> setup (ok, about .02 seconds slower to be exact).


Did you add in the time needed to load cl (a prerequisite for cl-seq
and cl-extra), cl-seq (for remove-if-not), and cl-extra (for mapcan)?

:-)


> This is quite amazing to me -- I thought lambda's are function
> calls, and function calls are slow, at least on a CISC CPU like
> the P4 that I'm running on.


Lisp function calls are relatively slow, but you can't determine
how many functions are called just by looking at the code.

Also, did you try byte-compiling the code?  Eric's code would probably
benefit the most, because of the lambda form.

--
Kevin Rodgers