From: Stefan Monnier <monnier@iro.umontreal.ca>
To: emacs-devel@gnu.org
Subject: Re: pure-fns in byte-opt.el
Date: Wed, 26 Jul 2017 08:58:24 -0400 [thread overview]
Message-ID: <jwv1sp3e4x7.fsf-monnier+gmane.emacs.devel@gnu.org> (raw)
In-Reply-To: 7ef8e35a-d236-5158-f2eb-85f01da87a2e@gmail.com
> I see. That's not what I understood to be usually meant by "pure":
> although both arguments are pointers to the same address in memory,
> the contents of that address have been modified in the meantime.
> In that sense, haven't the two calls to string-to-char been passed
> different values (albeit stored in the same memory location)?
If you think of Haskell types:
string-to-char :: String -> IO Char
and that's because in order to implement string-to-char, you need to use
aref :: Array α -> Int -> IO α
> In other words, I don't see your example as proving that
> string-to-char is impure; instead, it just looks like a pure function
> that's passed two different values. As a concrete example, is the
> following a proof that string-to-syntax is impure? If so, it should be
> removed from our list of pure functions :)
There are different notions of purity, indeed. Which is why I replied
to Andreas saying that just because string-to-char is not strictly
speaking pure, I don't see why adding it to pure-fns would
break anything.
Stefan
next prev parent reply other threads:[~2017-07-26 12:58 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-25 2:06 pure-fns in byte-opt.el Mark Oteiza
2017-07-25 8:14 ` Andreas Schwab
2017-07-25 14:16 ` Stefan Monnier
2017-07-25 20:57 ` Philipp Stephani
2017-07-25 21:27 ` Stefan Monnier
2017-07-25 22:28 ` Clément Pit-Claudel
2017-07-26 0:08 ` Stefan Monnier
2017-07-26 7:39 ` Clément Pit-Claudel
2017-07-26 12:58 ` Stefan Monnier [this message]
2017-07-28 17:45 ` Philipp Stephani
2017-07-28 17:49 ` Stefan Monnier
2017-07-28 17:52 ` Philipp Stephani
2017-07-28 22:20 ` Stefan Monnier
2017-09-24 7:31 ` Philipp Stephani
2017-09-24 16:23 ` Stefan Monnier
2017-09-25 22:06 ` Richard Stallman
2017-09-26 0:25 ` Stefan Monnier
2020-07-25 19:53 ` Philipp Stephani
2020-07-25 19:58 ` Stefan Monnier
2020-07-25 20:08 ` Philipp Stephani
2020-07-25 20:59 ` Stefan Monnier
2020-07-29 14:21 ` Philipp Stephani
2020-07-29 14:25 ` Stefan Monnier
2017-09-24 16:26 ` Drew Adams
2017-07-26 1:00 ` Mark Oteiza
2017-07-26 14:33 ` Eli Zaretskii
2017-07-27 2:36 ` Mark Oteiza
2017-07-27 2:46 ` Stefan Monnier
2017-07-29 16:43 ` Mark Oteiza
2017-07-29 17:22 ` Eli Zaretskii
2017-07-29 19:48 ` Mark Oteiza
2017-07-29 20:03 ` Andreas Schwab
2017-07-29 20:14 ` Mark Oteiza
2017-07-27 17:06 ` Eli Zaretskii
2017-07-28 0:24 ` Mark Oteiza
2017-07-28 7:02 ` Eli Zaretskii
2017-07-29 1:24 ` Mark Oteiza
2017-07-29 7:24 ` Eli Zaretskii
2017-07-29 16:34 ` Mark Oteiza
2017-07-29 17:21 ` Eli Zaretskii
2017-09-24 7:34 ` Philipp Stephani
2017-09-24 16:24 ` Stefan Monnier
2017-09-24 23:22 ` John Wiegley
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