# Evolution **URL:** https://forums.swift.org/c/evolution/18.md [Latest](https://forums.swift.org/latest.md) · [Categories](https://forums.swift.org/categories.md) · [Tags](https://forums.swift.org/tags.md) --- ## [About the Evolution category](https://forums.swift.org/t/about-the-evolution-category/7454)
**Author:** [@Nicole\_Jacque](https://forums.swift.org/u/Nicole_Jacque)\ **Replies:** 0
Topics related to the Swift Evolution Process. --- ## ["New Codable" prototype available for feedback](https://forums.swift.org/t/new-codable-prototype-available-for-feedback/85186)
**Author:** [@kperryua](https://forums.swift.org/u/kperryua)\ **Replies:** 88\ **Last updated:** [November 11, 2026, 4:30am UTC](https://forums.swift.org/t/new-codable-prototype-available-for-feedback/85186 "2026-11-11T04:30:44Z")
(Apologies for the re-post. We thought it best to create a new topic for increased visibility since some might not be following the original thread.) Hello again Swift Community! Here we are, almost a full year after m… --- ## [SE-0556: Cell, ConstCell, and Volatile](https://forums.swift.org/t/se-0556-cell-constcell-and-volatile/89988)
**Author:** [@Jumhyn](https://forums.swift.org/u/Jumhyn)\ **Replies:** 54\ **Last updated:** [November 11, 2026, 12:41am UTC](https://forums.swift.org/t/se-0556-cell-constcell-and-volatile/89988 "2026-11-11T00:41:20Z")
Hello, Swift community! The review of SE-0556: Cell, ConstCell, and Volatile begins now and runs through November 10th, 2026. Reviews are an important part of the Swift evolution process. All review feedback should be … --- ## [SE-0558: Bulk update operations for \`MutableSpan\` and \`MutableRawSpan\`](https://forums.swift.org/t/se-0558-bulk-update-operations-for-mutablespan-and-mutablerawspan/90048)
**Author:** [@Joe\_Groff](https://forums.swift.org/u/Joe_Groff)\ **Replies:** 8\ **Last updated:** [November 10, 2026, 11:40pm UTC](https://forums.swift.org/t/se-0558-bulk-update-operations-for-mutablespan-and-mutablerawspan/90048 "2026-11-10T23:40:31Z")
Hi everyone. The review of SE-0558, Bulk update operations for MutableSpan and MutableRawSpan, begins now and runs through October 28, 2026. Reviews are an important part of the Swift evolution process. All review feedb… --- ## [Conform Never to CustomStringConvertible](https://forums.swift.org/t/conform-never-to-customstringconvertible/90617)
**Author:** [@Dmitriy\_Ignatyev](https://forums.swift.org/u/Dmitriy_Ignatyev)\ **Replies:** 19\ **Last updated:** [November 10, 2026, 10:33pm UTC](https://forums.swift.org/t/conform-never-to-customstringconvertible/90617 "2026-11-10T22:33:22Z")
Introduction Following the precedent set by proposals like SE-0215 (Equatable/Hashable) and the more recent adoption of Codable for Never, I would like to pitch adding CustomStringConvertible and CustomDebugStringConvert… --- ## [\[Pitch\] Add Issue Capturing & Test-Utility-specific module to Swift Testing](https://forums.swift.org/t/pitch-add-issue-capturing-test-utility-specific-module-to-swift-testing/90397)
**Author:** [@younata](https://forums.swift.org/u/younata)\ **Replies:** 5\ **Last updated:** [November 10, 2026, 10:27pm UTC](https://forums.swift.org/t/pitch-add-issue-capturing-test-utility-specific-module-to-swift-testing/90397 "2026-11-10T22:27:29Z")
Hello everyone, The Swift Testing Workgroup has been discussing this as a pre-pitch for ~1.5 months now. This one grew out of the pitch for polling confirmations, and I feel it's past time to bring it to a wider audienc… --- ## [\[Pitch\] Equatable and Hashable conformances for the span family](https://forums.swift.org/t/pitch-equatable-and-hashable-conformances-for-the-span-family/90475)
**Author:** [@clintonpi](https://forums.swift.org/u/clintonpi)\ **Replies:** 8\ **Last updated:** [November 10, 2026, 7:43pm UTC](https://forums.swift.org/t/pitch-equatable-and-hashable-conformances-for-the-span-family/90475 "2026-11-10T19:43:53Z")
Hello everyone, Span, MutableSpan and OutputSpan should conform to Equatable and Hashable when their Element does, and RawSpan, MutableRawSpan and OutputRawSpan should conform unconditionally. Values of these types shou… --- ## [Swift on the GPU](https://forums.swift.org/t/swift-on-the-gpu/90299)
**Author:** [@drecothedev](https://forums.swift.org/u/drecothedev)\ **Replies:** 7\ **Last updated:** [November 10, 2026, 6:24pm UTC](https://forums.swift.org/t/swift-on-the-gpu/90299 "2026-11-10T18:24:30Z")
With the increase in GPU capabilities and expectations, I started to think about the possibility of system level programming with Swift, specifically for the GPU. Something Similar to that of Mojo? I started to work on … --- ## [\[Rejected\] SE-0554: Deployment target conditional compilation](https://forums.swift.org/t/rejected-se-0554-deployment-target-conditional-compilation/90589)
**Author:** [@xwu](https://forums.swift.org/u/xwu)\ **Replies:** 2\ **Last updated:** [November 9, 2026, 4:50pm UTC](https://forums.swift.org/t/rejected-se-0554-deployment-target-conditional-compilation/90589 "2026-11-09T16:50:59Z")
Hi all, The review of SE-0554: Deployment target conditional compilation concluded on October 12, 2026. After extended consideration, the language steering group has decided to reject the proposal. The group felt that … --- ## [SE-0554: Deployment target conditional compilation](https://forums.swift.org/t/se-0554-deployment-target-conditional-compilation/89822)
**Author:** [@xwu](https://forums.swift.org/u/xwu)\ **Replies:** 44\ **Last updated:** [November 9, 2026, 2:46pm UTC](https://forums.swift.org/t/se-0554-deployment-target-conditional-compilation/89822 "2026-11-09T14:46:32Z")
Hi all, The review of SE-0554: Deployment target conditional compilation beings now and runs through October 12, 2026. Reviews are an important part of the Swift evolution process. All review feedback should be either … --- ## ["Relaxed" floating-point operators](https://forums.swift.org/t/relaxed-floating-point-operators/90050)
**Author:** [@scanon](https://forums.swift.org/u/scanon)\ **Replies:** 35\ **Last updated:** [November 8, 2026, 7:13pm UTC](https://forums.swift.org/t/relaxed-floating-point-operators/90050 "2026-11-08T19:13:29Z")
Proposal here: Draft of relaxed floating-point operators. by stephentyrone · Pull Request #3545 · swiftlang/swift-evolution · GitHub Summary of changes Define operators on floating-point types that permit the compiler … --- ## [\[Pitch #2\] Called-once function types](https://forums.swift.org/t/pitch-2-called-once-function-types/90515)
**Author:** [@tshortli](https://forums.swift.org/u/tshortli)\ **Replies:** 32\ **Last updated:** [November 8, 2026, 1:49am UTC](https://forums.swift.org/t/pitch-2-called-once-function-types/90515 "2026-11-08T01:49:06Z")
Hello Swift Evolution! This is the second pitch for a language feature that lets you annotate function types as executing exactly once or at most once: func callOnce(\_ c: @once () -\> Void) { c() c() // error: 'c' i… --- ## [Negated type patterns in \`catch\`](https://forums.swift.org/t/negated-type-patterns-in-catch/90317)
**Author:** [@theoriginalbit](https://forums.swift.org/u/theoriginalbit)\ **Replies:** 6\ **Last updated:** [November 7, 2026, 6:18am UTC](https://forums.swift.org/t/negated-type-patterns-in-catch/90317 "2026-11-07T06:18:09Z")
Has anyone else wanted a negated type pattern in catch? I couldn't find an earlier thread on this. Particularly since the introduction of typed-throws (SE-0413) I find myself often writing a forwarding clause when a do … --- ## [SE-0564: Split Continuations](https://forums.swift.org/t/se-0564-split-continuations/90467)
**Author:** [@Joe\_Groff](https://forums.swift.org/u/Joe_Groff)\ **Replies:** 14\ **Last updated:** [November 6, 2026, 8:38pm UTC](https://forums.swift.org/t/se-0564-split-continuations/90467 "2026-11-06T20:38:26Z")
Hi everybody. The review of SE-0564, Split Continuations, begins now and runs through November 18, 2026. Reviews are an important part of the Swift evolution process. All review feedback should be either on this forum t… --- ## [\[Pitch\] Split continuation](https://forums.swift.org/t/pitch-split-continuation/90096)
**Author:** [@FranzBusch](https://forums.swift.org/u/FranzBusch)\ **Replies:** 13\ **Last updated:** [November 6, 2026, 9:57am UTC](https://forums.swift.org/t/pitch-split-continuation/90096 "2026-11-06T09:57:21Z")
Hi everyone, Here is a pitch to make working with continuations easier and enable a more performant way to resume them in cases where the current execution context can be donated: \[Concurrency\] Proposal for split contin… --- ## [Pitch: Single-yield functions](https://forums.swift.org/t/pitch-single-yield-functions/90319)
**Author:** [@meg-gupta](https://forums.swift.org/u/meg-gupta)\ **Replies:** 21\ **Last updated:** [November 6, 2026, 3:46am UTC](https://forums.swift.org/t/pitch-single-yield-functions/90319 "2026-11-06T03:46:41Z")
Hi everyone, This is a pitch to introduce single-yield functions to the language. Single-yield functions are declared by writing yield in the result position: func f() -\> yield T // yields an owned value func … --- ## [SE-0563: Improve Interaction Between \`@main\` and Top-Level Code](https://forums.swift.org/t/se-0563-improve-interaction-between-main-and-top-level-code/90434)
**Author:** [@hborla](https://forums.swift.org/u/hborla)\ **Replies:** 7\ **Last updated:** [November 5, 2026, 10:55pm UTC](https://forums.swift.org/t/se-0563-improve-interaction-between-main-and-top-level-code/90434 "2026-11-05T22:55:28Z")
Hello, Swift community! The review of SE-0563: Improve Interaction Between @main and Top-Level Code begins now and runs through November 17, 2026. Reviews are an important part of the Swift evolution process. All revie… --- ## [\[Pitch\] Introduce a way to annotate functions that are called at most once](https://forums.swift.org/t/pitch-introduce-a-way-to-annotate-functions-that-are-called-at-most-once/89088)
**Author:** [@xedin](https://forums.swift.org/u/xedin)\ **Replies:** 117\ **Last updated:** [November 5, 2026, 10:02pm UTC](https://forums.swift.org/t/pitch-introduce-a-way-to-annotate-functions-that-are-called-at-most-once/89088 "2026-11-05T22:02:36Z")
Hello Swift community! This pitch introduces a @called(once) attribute to model at-most once execution of a function. Making function execution behavior visible to the compiler has two advantages. First, it makes it pos… --- ## [\`NDEBUG\` vs SPM dependencies](https://forums.swift.org/t/ndebug-vs-spm-dependencies/90458)
**Author:** [@tera](https://forums.swift.org/u/tera)\ **Replies:** 1\ **Last updated:** [November 5, 2026, 7:54am UTC](https://forums.swift.org/t/ndebug-vs-spm-dependencies/90458 "2026-11-05T07:54:29Z")
DEBUG is being passed to SPM dependencies when the app configuration is named "debug", "development" or contains those names as substrings - good to know. RELEASE is not being passed, although typically RELEASE is the o… --- ## [\[Pitch\] Standard name for common low level C interfaces](https://forums.swift.org/t/pitch-standard-name-for-common-low-level-c-interfaces/89825)
**Author:** [@ian-twilightcoder](https://forums.swift.org/u/ian-twilightcoder)\ **Replies:** 43\ **Last updated:** [November 4, 2026, 8:57pm UTC](https://forums.swift.org/t/pitch-standard-name-for-common-low-level-c-interfaces/89825 "2026-11-04T20:57:47Z")
There continues to be a need for Swift code to directly use low level C interfaces provided by the operating system platform. These are exposed by the modules in stdlib/public/Platform including Glibc, CRT, WASILibc, And… --- ## [Pitch: Back-deployment for fixed-layout value types - #3571](https://forums.swift.org/t/pitch-back-deployment-for-fixed-layout-value-types-3571/90446)
**Author:** [@Douglas\_Gregor](https://forums.swift.org/u/Douglas_Gregor)\ **Replies:** 9\ **Last updated:** [November 4, 2026, 7:02pm UTC](https://forums.swift.org/t/pitch-back-deployment-for-fixed-layout-value-types-3571/90446 "2026-11-04T19:02:51Z")
Hi all, @tshortli and I found a way to do back-deployment for a limited class of types, specifically, @frozen struct and enum types with a fixed layout. The proposal here is to extend the existing @backDeployed(before:) … --- ## [SE-0559: Add \`bidiClass\` to \`Unicode.Scalar.Properties\`](https://forums.swift.org/t/se-0559-add-bidiclass-to-unicode-scalar-properties/90186)
**Author:** [@Douglas\_Gregor](https://forums.swift.org/u/Douglas_Gregor)\ **Replies:** 7\ **Last updated:** [November 4, 2026, 3:21pm UTC](https://forums.swift.org/t/se-0559-add-bidiclass-to-unicode-scalar-properties/90186 "2026-11-04T15:21:03Z")
Hello, Swift community! The review of SE-0559: Add bidiClass to Unicode.Scalar.Properties begins now and runs through November 4, 2026. Reviews are an important part of the Swift evolution process. All review feedback … --- ## [Idea: Add dropLast(while:) to BidirectionalCollection](https://forums.swift.org/t/idea-add-droplast-while-to-bidirectionalcollection/90460)
**Author:** [@ravindu](https://forums.swift.org/u/ravindu)\ **Replies:** 0\ **Last updated:** [November 4, 2026, 1:59pm UTC](https://forums.swift.org/t/idea-add-droplast-while-to-bidirectionalcollection/90460 "2026-11-04T13:59:00Z")
I often need to drop elements from the end of a sequence based on a condition (for example, trimming trailing whitespace or filtering out values). Currently Swift only offers drop(while:) to drop from the start of a coll… --- ## [\[Pitch\] Allowing Multiple Major Versions of a Package](https://forums.swift.org/t/pitch-allowing-multiple-major-versions-of-a-package/90326)
**Author:** [@bripeticca](https://forums.swift.org/u/bripeticca)\ **Replies:** 14\ **Last updated:** [November 3, 2026, 8:20pm UTC](https://forums.swift.org/t/pitch-allowing-multiple-major-versions-of-a-package/90326 "2026-11-03T20:20:26Z")
This pitch is based on some investigative and prototype work that I've developed over the last few months. The goal with this feature is to extend the versatility of SwiftPM as a sophisticated package manager tool that g… --- ## [SE-0562: Ownership for Subscript Parameters](https://forums.swift.org/t/se-0562-ownership-for-subscript-parameters/90429)
**Author:** [@scanon](https://forums.swift.org/u/scanon)\ **Replies:** 0\ **Last updated:** [November 3, 2026, 8:15pm UTC](https://forums.swift.org/t/se-0562-ownership-for-subscript-parameters/90429 "2026-11-03T20:15:56Z")
Dearest Swift community, The review of SE-0562: Ownership for Subscript Parameters begins now and runs through November 17, 2026. Reviews are an important part of the Swift evolution process. All review feedback should… --- ## [Explicit Copies Mode](https://forums.swift.org/t/explicit-copies-mode/81779)
**Author:** [@kavon](https://forums.swift.org/u/kavon)\ **Replies:** 23\ **Last updated:** [November 3, 2026, 11:41am UTC](https://forums.swift.org/t/explicit-copies-mode/81779 "2026-11-03T11:41:23Z")
I’ve been prototyping a new feature aimed at performance-conscious programmers that removes the mystery around when copies (such as retains) of values occur in their code. The idea is that you can ask the compiler to for… --- ## [\[Accepted\] SE-0528: Non-\`Copyable\` \`Continuation\`](https://forums.swift.org/t/accepted-se-0528-non-copyable-continuation/86533)
**Author:** [@Joe\_Groff](https://forums.swift.org/u/Joe_Groff)\ **Replies:** 6\ **Last updated:** [November 3, 2026, 5:58am UTC](https://forums.swift.org/t/accepted-se-0528-non-copyable-continuation/86533 "2026-11-03T05:58:23Z")
Hi everyone. The review of SE-0528, Non-Copyable Continuation, concluded on April 28, 2026. The Language Steering Group has decided the proposal should be accepted with modifications. In order to maintain naming consiste… --- ## [SE-0499 marked as Implemented (Swift 6.4), but isn't fully implemented](https://forums.swift.org/t/se-0499-marked-as-implemented-swift-6-4-but-isnt-fully-implemented/90399)
**Author:** [@Karl](https://forums.swift.org/u/Karl)\ **Replies:** 0\ **Last updated:** [November 3, 2026, 3:03am UTC](https://forums.swift.org/t/se-0499-marked-as-implemented-swift-6-4-but-isnt-fully-implemented/90399 "2026-11-03T03:03:07Z")
Hello, I tried to make a String of a non-copyable type: assert(..., "Unexpected foo: \\(myNonCopyableValue)") but it appears that DefaultStringInterpolation does not support non-copyable types. Neither is there a Strin… --- ## [SE-0561: Span-based access to \`Optional\`'s storage](https://forums.swift.org/t/se-0561-span-based-access-to-optional-s-storage/90398)
**Author:** [@ben-cohen](https://forums.swift.org/u/ben-cohen)\ **Replies:** 0\ **Last updated:** [November 3, 2026, 1:47am UTC](https://forums.swift.org/t/se-0561-span-based-access-to-optional-s-storage/90398 "2026-11-03T01:47:46Z")
Hi Swift community, The review of SE-0561: Span-based access to Optional's storage begins now and runs through November 13th, 2026. Reviews are an important part of the Swift evolution process. All review feedback shou… --- ## [Reject likely-unsound script variable forward references](https://forums.swift.org/t/reject-likely-unsound-script-variable-forward-references/85996)
**Author:** [@hamishknight](https://forums.swift.org/u/hamishknight)\ **Replies:** 4\ **Last updated:** [November 2, 2026, 10:52pm UTC](https://forums.swift.org/t/reject-likely-unsound-script-variable-forward-references/85996 "2026-11-02T22:52:37Z")
Hey folks, I'm back again with another proposal to further tighten up the rules around forward references to variables (previous one here). This one concerns variables at the top level of a script file (main.swift). Tod… [Next page](https://forums.swift.org/c/evolution/18.md?page=1)