From: "joshuay03 (Joshua Young) via ruby-core" <ruby-core@ml.ruby-lang.org>
To: ruby-core@ml.ruby-lang.org
Cc: "joshuay03 (Joshua Young)" <noreply@ruby-lang.org>
Subject: [ruby-core:114314] [Ruby master Feature#19787] Add Enumerable#uniq_map, Enumerable::Lazy#uniq_map, Array#uniq_map and Array#uniq_map!
Date: Mon, 31 Jul 2023 10:13:10 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-104016.20230731101309.52912@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-19787.20230729141300.52912@ruby-lang.org
Issue #19787 has been updated by joshuay03 (Joshua Young).
> Is `.map { ... }.uniq` such a very frequent idiom?
I work on a Rails codebase and it's most commonly used to iterate through foreign keys / associated records and get the unique values (quite often in tests). That's the only real frequent use case I've come across, but I would say that outside of that, it's not an uncommon chaining pattern either.
> `.uniq_map { ... }` is not as concise as `.map { ... }.uniq`.
I'm a bit mixed on this point. I see where you're coming from, and I think the same argument can be made about `#flat_map` and `#filter_map`. But it follows a similar naming pattern where the alternative method is in the name, so I personally feel like it's it's equally as concise?
I would also like to point out that with `#uniq_map`, you don't need to read all the way to `.uniq` before inferring the output. This might help when the body of the `#map` is quite complex, but you could argue that this is a code quality / style problem...
```
some_array.map do |item|
if some_condition
some_method(item)
else
some_other_method(item)
end
end.uniq
# vs
some_array.uniq_map do |item|
if some_condition
some_method(item)
else
some_other_method(item)
end
end
```
> Scala doesn't seem to provide `uniqMap`.
Sorry, this is the first Ruby issue I've created or being involved with, so I'm not sure why this was pointed out. Is this a usual consideration for new features?
> Considering the above, I think the motivation is too weak to provide `uniq_map`.
Your points are very valid, and I appreciate the response. What is the usual process for deciding on whether or not to accept a feature?
----------------------------------------
Feature #19787: Add Enumerable#uniq_map, Enumerable::Lazy#uniq_map, Array#uniq_map and Array#uniq_map!
https://bugs.ruby-lang.org/issues/19787#change-104016
* Author: joshuay03 (Joshua Young)
* Status: Open
* Priority: Normal
----------------------------------------
I would like to propose a collection of new methods, `Enumerable#uniq_map`, `Enumerable::Lazy#uniq_map`, `Array#uniq_map` and `Array#uniq_map!`.
TL;DR: It's a drop in replacement for `.map { ... }.uniq`, with (hopefully) better performance.
I've quite often had to map over an array and get its unique elements. It occurred to me when doing so recently that Ruby doesn't have a short form method for doing that, similar to how `.flat_map { ... }` replaces `.map { ... }.flatten` and `.filter_map { ... }` replaces `.map { ... }.compact` (with minor differences). I think these new methods could be beneficial both in terms of better performance and writing more succinct code.
I've got a draft PR up with some initial benchmarks in the description: https://github.com/ruby/ruby/pull/8140.
--
https://bugs.ruby-lang.org/
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next prev parent reply other threads:[~2023-07-31 10:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-29 14:13 [ruby-core:114309] [Ruby master Feature#19787] Add Enumerable#uniq_map, Enumerable::Lazy#uniq_map, Array#uniq_map and Array#uniq_map! joshuay03 (Joshua Young) via ruby-core
2023-07-31 8:40 ` [ruby-core:114313] " mame (Yusuke Endoh) via ruby-core
2023-07-31 10:13 ` joshuay03 (Joshua Young) via ruby-core [this message]
2023-07-31 14:22 ` [ruby-core:114320] " austin (Austin Ziegler) via ruby-core
2023-07-31 14:50 ` [ruby-core:114321] " rubyFeedback (robert heiler) via ruby-core
2024-03-16 3:30 ` [ruby-core:117198] " joshuay03 (Joshua Young) via ruby-core
2024-03-16 3:40 ` [ruby-core:117199] " joshuay03 (Joshua Young) via ruby-core
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