alexandria-devel April 2007

alexandria-devel@common-lisp.net

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2 discussions

[alexandria-devel] darcs patch: Add #.#+ readtime conditional functions.
by asf＠boinkor.net 02 Oct '09

02 Oct '09

Mon Oct 16 10:00:31 CEST 2006 asf(a)boinkor.net * Add #.#+ readtime conditional functions. * This adds functions that can be used in #+#. readtime conditionals, for example: #+#.(alexandria:read-if (find-package :asdf-install)) :yay #+#.(alexandria:read-if-fbound :install :asdf-install :exportedp t) :yay * included in the patch is a commented-out portion that allows the user to activate a #? read syntax. I'm not sure if that fits into the conservativism constraints.

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[alexandria-devel] A clean-room implementation of FILTER-IF from Paul Graham's "On Lisp."
by Samium Gromoff 23 Apr '07

23 Apr '07

Good day, perhaps the function below meets the Alexandria's standards for conservativeness/usefulness: (defun filter-if (fn &rest sequences) (labels ((iterate (acc sequences) (if (notany #'null sequences) (iterate (if-let ((testval (apply fn (mapcar #'car sequences)))) (cons testval acc) acc) (mapcar #'cdr sequences)) acc))) (nreverse (iterate nil sequences)))) The idea, but not the implementation, was taken from Paul Graham's book "On Lisp". Also, i cannot come up with a good docstring, so such one would be appreciated. regards, Samium Gromoff

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alexandria-devel April 2007