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Re: master 3e5298f: Improve performance of seq-union
From: |
Robert Pluim |
Subject: |
Re: master 3e5298f: Improve performance of seq-union |
Date: |
Mon, 27 Sep 2021 17:21:17 +0200 |
>>>>> On Mon, 27 Sep 2021 17:07:39 +0200, Lars Ingebrigtsen <larsi@gnus.org>
>>>>> said:
Lars> Robert Pluim <rpluim@gmail.com> writes:
>> Utterly idle thought: would packages that tend to generate long lists
>> and reverse them, such as Gnus, benefit from a builtin-in queue data
>> type that supported efficient appending?
Lars> A new data structure that has both head and a tail pointer? I think
Lars> you'd be hard pressed to get that to be faster than push+nreverse
unless
Lars> you implement it in C -- nreverse is very fast.
Intuitively, such a data structure needs to do less work than
nreverse, but it has to maintain the tail pointer, which should be a
net win.
Lars> But I could be wrong.
Iʼve not implemented and measured it :-)
Robert
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