From: "Linus Björnstam" <linus.internet@fastmail.se>
To: "Tim Meehan" <btmeehan@gmail.com>, guile-user <guile-user@gnu.org>
Subject: Re: delay and force
Date: Thu, 10 Jun 2021 07:30:15 +0200 [thread overview]
Message-ID: <b993a8cb-376b-45ab-99f3-15c8ec29d009@www.fastmail.com> (raw)
In-Reply-To: <CACgrOxLgGCHz3uPd70J=q56YDU0XYroBY9qF4HgCQLkuwMaSTg@mail.gmail.com>
You can see a version of them used in srfi-41. I do believe I use them in my old implementation of rackets for loops for guile. For/foldr I used them as a way to ensure that the next iteration was evaluated only once (despite being possible to call it several times) to avoid quadratic behaviour.
I don't really think they are used that often, since when you need laziness you would probably reach for srfi-41 (which is horribly slow) or generators (srfi-158).
I see them as a primitive mostly for macro writers, to be honest. It is useful if you want to handle a computation back to the user but want to make sure it is run at most one time. That is mostly how I have seen them used (and used them myself), at least.
--
Linus Björnstam
On Thu, 10 Jun 2021, at 07:08, Tim Meehan wrote:
> Are there any good examples of "medium-sized" programs that use delay and
> force? I have seen the documentation examples, but I am curious about how
> it is used by other people in larger projects.
>
prev parent reply other threads:[~2021-06-10 5:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 5:08 delay and force Tim Meehan
2021-06-10 5:30 ` Linus Björnstam [this message]
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