Structured concurrency A lot of the sessions at this years' WWDC related to the new concurrency model in Swift. A central part of this model is the concept of structured concurrency, which enables concurrent execution of asynchronous code. The language features are now available in the latest Xcode beta, and this proposal provides lots of background on this major Swift language evolution. Posted on June 25, 2021 | evolution concurrency
Introducing Swift Collections Like the Swift Algorithms package before it, the recently released Swift Collections package is intended to incubate new functionality for the Swift Standard Library. In this post, Karoy Lorentey from the Swift Standard Library team gives us a brief tour of what the package provides. Posted on May 14, 2021 | evolution open-source collection sequence
Actors are reference types, but why classes? The recently announced Swift Concurrency Roadmap includes the proposal of an Actor reference type, similar to a class type. In this whitepaper, Chris Lattner explores the behavior and requirements of actors and proposes that Actor types be modeled as a new kind of nominal reference type in Swift. Posted on December 16, 2020 | concurrency evolution actor
Codable synthesis for enums with associated values Swift 4 introduced support for automatically synthesizing conformance to the Encodable and Decodable protocols. It's a useful feature, most likely used by any application which handles JSON-based network requests. This Swift evolution pitch from Dario Rexin proposes extending auto-synthesis of these conformances to enums with associated values. I'm sure we will see this in an upcoming Swift version. Posted on December 8, 2020 | evolution enum codable
Availability checking for protocol conformances Swift's availability checking feature currently allows us to check if a referenced declaration is available at runtime. In this post from the official Swift forums, Slava Pestov details an extension to this feature which provides the ability to check the availability of protocol conformances. Posted on November 30, 2020 | evolution protocol
[Proposal] Static member lookup on protocol metatypes Swift currently supports static member lookup on concrete types. This improves call-site legibility by enabling us to use leading dot syntax when accessing static values. In this Swift evolution pitch, Sam Lazarus proposes extending static member lookup to protocol metatypes. This would be a nice addition, and would not have any effect of source of API stability. Posted on November 22, 2020 | evolution protocol
Swift Concurrency Roadmap This post from the official Swift forums outlines the Swift Concurrency Roadmap. The goal of this roadmap is to make concurrent programming in Swift convenient, efficient, and safe. There is a lot to unpack in this post, but it's definitely worth reading, and there are some great language features planned for the first phase of the roadmap. Posted on November 9, 2020 | concurrency evolution
Placeholder types Building on a previous Swift evolution thread, Frederick Kellison-Linn pitches a proposal to add what he calls placeholder types to Swift. These placeholder types could be used when we want to explicitly provide some type information but also want the compiler to infer some type information. Posted on November 4, 2020 | evolution compiler
Unlock Existential Types for All Protocols Swift currently allows protocols that meet certain criteria to be used as types. Using a protocol in such a way essentially creates an existential type. However, protocols with associated type or self requirements cannot currently be used to create such existential types. This Swift evolution pitch proposes removing this restriction. Posted on October 22, 2020 | evolution protocol existential
Result builders This Swift evolution proposal outlines the motivation and design for Result Builders, the Swift language feature previously known as Function Builders. Result Builders have been an available feature since Swift 5.1, albeit slightly hidden, and its implementation and capabilities have evolved since then. Posted on October 18, 2020 | evolution result builders