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Re: master d62766305a: Add `take` and `ntake` (bug#56521)
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From: |
Sam Steingold |
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Subject: |
Re: master d62766305a: Add `take` and `ntake` (bug#56521) |
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Date: |
Mon, 18 Jul 2022 18:57:04 -0400 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (darwin) |
> * Philip Kaludercic <cuvyvcx@cbfgrb.arg> [2022-07-18 18:56:24 +0000]:
>
> Sam Steingold <sds@gnu.org> writes:
>
>>> * Mattias Engdegård <znggvnfr@npz.bet> [2022-07-17 11:47:25 -0400]:
>>>
>>> branch: master
>>> commit d62766305ad8fe6ca1695341c34b9836d051e3cb
>>> Author: Mattias Engdegård <mattiase@acm.org>
>>> Commit: Mattias Engdegård <mattiase@acm.org>
>>>
>>> Add `take` and `ntake` (bug#56521)
>>>
>>> These are useful list primitives, complementary to `nthcdr`.
>>
>> How are these better than the venerable butlast and nbutlast?
>> https://www.gnu.org/software/emacs/manual/html_node/elisp/List-Elements.html#index-butlast
>> note that butlast and nbutlast have a very long Lisp history, they
>> appear also in Common Lisp and many lisps before that.
>
> The immediate advantage I recognise is that you don't need to determine
> the length of the list if you are actually just interested in the first
> n, not just not-interested in the last m.
good point, thank you!
in that case you might consider modifying (n)butlast to
call (n)take to make them faster.
--
Sam Steingold (http://sds.podval.org/) on darwin Ns 10.3.2113
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