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From: | Michael Heerdegen |
Subject: | Re: thunk.el: Document that thunk-force == funcall? |
Date: | Tue, 17 Nov 2020 22:07:33 +0100 |
User-agent: | Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
Tomas Hlavaty <tom@logand.com> writes: > why would you delay such boolean value in a thunk? > > to avoid computing the value in case it is not used at all? > > when something-is-the-case how can it take long to find out? why it > cannot be substituted with t at think-time? The result might not be defined at think time. It might depend on "the environment". Say the code loops over a list of files or so (not known at think time). The thunk could "contain" a test that might take long (e.g. something that might need to look at the file's contents) but the result is interesting only sometimes, depending on the result of other tests (also not known at think time). Michael.
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