From: Andrea Corallo via "Emacs development discussions." <emacs-devel@gnu.org>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Zhu Zihao <all_but_last@163.com>, Tomas Hlavaty <tom@logand.com>,
emacs-devel@gnu.org
Subject: Re: named-let
Date: Tue, 12 Jan 2021 09:24:46 +0000 [thread overview]
Message-ID: <xjfmtxeecdd.fsf@sdf.org> (raw)
In-Reply-To: <jwvo8hv3ue7.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Mon, 11 Jan 2021 18:57:36 -0500")
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>>> [ TCO has also undesirable interactions with debugging/tracing, but
>>> I think that would be a secondary concern which should be
>>> manageable somehow. ]
>>
>> It's also a change in semantic as one must assume that `bar' is not
>> redefining `foo'.
>>
>> (defun foo ()
>> (bar)
>> (foo))
>
> I think there's a bit of confusion: you can have TCO without having to
> pay any attention to whether `bar` changes `foo`. True TCO will also
> avoid eating up stack space when you have code like
Yes, I was discussing Tail Recursion Eliminination (or self TCO).
Actually I was thinking one could even check if `foo' was redefined
before performing the TRE sequence (well I guess that's what the
byteinterpreter patches you've mentioned did), in this case we could
have it also at speed 2.
As a side note I think we could have full TCO in Emacs, but at the cost
of a relatively invasive patch and a some (probably small but hard
to quantify a priori) performance regression. Not sure it is
sufficiently important to justify that.
Andrea
next prev parent reply other threads:[~2021-01-12 9:24 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-09 1:43 named-let Stefan Monnier
2021-01-09 8:58 ` named-let tomas
2021-01-09 16:01 ` named-let Joost Kremers
2021-01-09 21:48 ` named-let Stefan Monnier
2021-01-09 15:23 ` named-let Tomas Hlavaty
2021-01-09 16:44 ` named-let Stefan Monnier
2021-01-09 17:03 ` named-let Helmut Eller
2021-01-09 18:43 ` named-let Stefan Monnier
2021-01-09 18:47 ` named-let Tomas Hlavaty
2021-01-10 18:49 ` named-let Zhu Zihao
2021-01-11 22:27 ` named-let Tomas Hlavaty
2021-01-11 22:36 ` named-let Stefan Monnier
2021-01-11 22:48 ` named-let Tomas Hlavaty
2021-01-11 22:50 ` named-let Andrea Corallo via Emacs development discussions.
2021-01-11 23:10 ` named-let Stefan Monnier
2021-01-11 23:28 ` named-let Andrea Corallo via Emacs development discussions.
2021-01-11 23:57 ` named-let Stefan Monnier
2021-01-12 9:24 ` Andrea Corallo via Emacs development discussions. [this message]
2021-01-12 18:07 ` named-let Stefan Monnier
2021-01-12 18:50 ` named-let Andrea Corallo via Emacs development discussions.
2021-01-12 9:13 ` named-let Helmut Eller
2021-01-13 8:11 ` named-let Zhu Zihao
2021-01-13 14:01 ` named-let Stefan Monnier
2021-01-11 22:40 ` named-let Andrea Corallo via Emacs development discussions.
2021-01-11 22:51 ` named-let Tomas Hlavaty
2021-01-11 23:04 ` named-let Andrea Corallo via Emacs development discussions.
2021-01-12 0:12 ` named-let Tomas Hlavaty
2021-01-20 19:44 ` named-let Stefan Monnier
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