Make `array::{try_from_fn, try_map}` and `Iterator::try_find` generic over `Try` #91286

scottmcm · 2021-11-27T08:38:32Z

This only updates unstable functions.

array::try_map didn't actually exist before; this adds it under the still-open tracking issue #79711 from the old PR #79713.

Tracking issue for the new trait: #91285

This would also solve the return type question in for the proposed Iterator::try_reduce in #87054

rust-highfive · 2021-11-27T08:38:35Z

r? @joshtriplett

(rust-highfive has picked a reviewer for you, use r? to override)

scottmcm · 2021-11-27T08:42:57Z

library/core/src/iter/traits/iterator.rs

    #[inline]
    #[unstable(feature = "try_find", reason = "new API", issue = "63178")]
-    fn try_find<F, R, E>(&mut self, f: F) -> Result<Option<Self::Item>, E>
+    fn try_find<F, R>(&mut self, f: F) -> ChangeOutputType<R, Option<Self::Item>>


I'm happy that this gets to remove the superfluous E here. I had previously added it in ca92b5a#diff-c552b2bf18fb3212fe93dd601ce487badf5e50faf9aeed4db7b0f6c22571ef01R2416 to make the ugly bound below happy -- and making that bound not so overly-restrictive is the genesis of this PR.

scottmcm · 2021-11-27T08:52:55Z

library/core/src/array/mod.rs

+    /// assert_eq!(c, Some(a));
+    /// ```
+    #[unstable(feature = "array_try_map", issue = "79711")]
+    pub fn try_map<F, R>(self, f: F) -> ChangeOutputType<R, [R::Output; N]>


If you're curious, rustdoc expands out the type alias here. Yes, it's not friendly once expanded:

joshtriplett · 2021-12-02T17:52:10Z

@bors r rollup=never

bors · 2021-12-02T17:52:15Z

📌 Commit 922abfafc367cec3a87a8bf87d1d9a653f47908a has been approved by joshtriplett

bors · 2021-12-02T18:45:50Z

⌛ Testing commit 922abfafc367cec3a87a8bf87d1d9a653f47908a with merge 26e9d09eab6c91ecc5e49dcfc6c7fb514cd1b77f...

bors · 2021-12-02T19:11:52Z

💔 Test failed - checks-actions

…r Try Fixes 85115 This only updates unstable functions. `array::try_map` didn't actually exist before, despite the tracking issue 79711 still being open from the old PR 79713.

scottmcm · 2021-12-02T19:28:27Z

Doh, conflicted with myself (#91301). I've removed the no-longer-needed #![feature] (and rebased).

@bors r=joshtriplett

bors · 2021-12-02T19:28:28Z

📌 Commit b96b9b4 has been approved by joshtriplett

bors · 2021-12-03T01:04:05Z

⌛ Testing commit b96b9b4 with merge 75920bfb43c87df5c6a46c29386ea4ff8a304ef2...

bors · 2021-12-03T04:14:02Z

💔 Test failed - checks-actions

rust-log-analyzer · 2021-12-03T04:14:39Z

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

scottmcm · 2021-12-03T05:01:42Z

I don't see anything in https://github.com/rust-lang-ci/rust/runs/4402890723 that actually failed?

Looks like dist-x86_64-apple just didn't run at all.

@bors retry

bors · 2021-12-03T10:15:14Z

⌛ Testing commit b96b9b4 with merge d47a6cc...

bors · 2021-12-03T13:20:05Z

☀️ Test successful - checks-actions
Approved by: joshtriplett
Pushing d47a6cc to master...

rust-timer · 2021-12-03T14:50:04Z

Finished benchmarking commit (d47a6cc): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression

…ttmcm Stabilize `array_from_fn` ## Overall Stabilizes `core::array::from_fn` ~~and `core::array::try_from_fn`~~ to allow the creation of custom infallible ~~and fallible~~ arrays. Signature proposed for stabilization here, tweaked as requested in the meeting: ```rust // in core::array pub fn from_fn<T, const N: usize, F>(_: F) -> [T; N]; ``` Examples in https://doc.rust-lang.org/nightly/std/array/fn.from_fn.html ## History * On 2020-08-17, implementation was [proposed](rust-lang#75644). * On 2021-09-29, tracking issue was [created](rust-lang#89379). * On 2021-10-09, the proposed implementation was [merged](bc8ad24). * On 2021-12-03, the return type of `try_from_fn` was [changed](rust-lang#91286 (comment)). ## Considerations * It is being assumed that indices are useful and shouldn't be removed from the callbacks * The fact that `try_from_fn` returns an unstable type `R: Try` does not prevent stabilization. Although I'm honestly not sure about it. * The addition or not of repeat-like variants is orthogonal to this PR. These considerations are not ways of saying what is better or what is worse. In reality, they are an attempt to move things forward, anything really. cc rust-lang#89379

Stabilize `array_from_fn` ## Overall Stabilizes `core::array::from_fn` ~~and `core::array::try_from_fn`~~ to allow the creation of custom infallible ~~and fallible~~ arrays. Signature proposed for stabilization here, tweaked as requested in the meeting: ```rust // in core::array pub fn from_fn<T, const N: usize, F>(_: F) -> [T; N]; ``` Examples in https://doc.rust-lang.org/nightly/std/array/fn.from_fn.html ## History * On 2020-08-17, implementation was [proposed](rust-lang/rust#75644). * On 2021-09-29, tracking issue was [created](rust-lang/rust#89379). * On 2021-10-09, the proposed implementation was [merged](rust-lang-ci/rust@bc8ad24). * On 2021-12-03, the return type of `try_from_fn` was [changed](rust-lang/rust#91286 (comment)). ## Considerations * It is being assumed that indices are useful and shouldn't be removed from the callbacks * The fact that `try_from_fn` returns an unstable type `R: Try` does not prevent stabilization. Although I'm honestly not sure about it. * The addition or not of repeat-like variants is orthogonal to this PR. These considerations are not ways of saying what is better or what is worse. In reality, they are an attempt to move things forward, anything really. cc rust-lang/rust#89379

rust-highfive assigned joshtriplett Nov 27, 2021

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scottmcm added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Nov 27, 2021

scottmcm commented Nov 27, 2021

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scottmcm mentioned this pull request Nov 27, 2021

Add a try_reduce method to the Iterator trait #87054

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Make array::{try_from_fn, try_map} and Iterator::try_find generic ove…

b96b9b4

…r Try Fixes 85115 This only updates unstable functions. `array::try_map` didn't actually exist before, despite the tracking issue 79711 still being open from the old PR 79713.

scottmcm force-pushed the residual-trait branch from 922abfa to b96b9b4 Compare December 2, 2021 19:24

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 2, 2021

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Dec 3, 2021

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 3, 2021

bors added the merged-by-bors This PR was explicitly merged by bors. label Dec 3, 2021

bors merged commit d47a6cc into rust-lang:master Dec 3, 2021

rustbot added this to the 1.59.0 milestone Dec 3, 2021

scottmcm deleted the residual-trait branch December 3, 2021 18:33

This was referenced Dec 4, 2021

Decide on generic-ness of functions like Iterator::try_find and array::try_map #85115

Closed

Tracking issue for array::try_map #79711

Open

Tracking issue for ? operator and try blocks (RFC 243, question_mark & try_blocks features) #31436

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c410-f3r mentioned this pull request Feb 18, 2022

Stabilize array_from_fn #94119

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Make `array::{try_from_fn, try_map}` and `Iterator::try_find` generic over `Try` #91286

Make `array::{try_from_fn, try_map}` and `Iterator::try_find` generic over `Try` #91286

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Make array::{try_from_fn, try_map} and Iterator::try_find generic over Try #91286

Make array::{try_from_fn, try_map} and Iterator::try_find generic over Try #91286

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Make `array::{try_from_fn, try_map}` and `Iterator::try_find` generic over `Try` #91286

Make `array::{try_from_fn, try_map}` and `Iterator::try_find` generic over `Try` #91286

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