select / filter from list
reddit / emacs

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pedzsanReddit · 2022-12-20 15:57

I am looking for is a function that takes two arguments: a predicate
(a function that takes one argument and returns nil/non-nil) and a
list and finds the first element of the list where predicate returns
non-nil.

It seems really basic but I can't find such a function.

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yyoncho · 2022-12-20 16:15

`seq-find`

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pedzsanReddit · 2022-12-20 16:27

Thanks!

I was just in the process of coming back and putting an update.

I used elisp-index-search of "filter" and was going through all the
hits and came across seq-filter.  see-find is better.  I also found
seq-remove which is another function I've been searching for.

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00-11 · 2022-12-20 18:00

`cl-find-if` or `seq-find`

You're not *filtering* the list/sequence; you're looking for the first
element that satisfies some condition. Filtering would return a
subsequence, not an element.

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JDRiverRun · 2022-12-20 18:45

And if you need to know the first matching *position* instead of the
value, `cl-position-if`.

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lastnamebird · 2022-12-20 20:59

I find it is useful to look at the source code for other functions
defined in the same file when I find a useful/similar function. In
this case, they should all be in seq.el.

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[deleted] · 2022-12-20 21:47

[deleted]