SE-0343 upgrades Swift’s support for top-level code – think main.swift in a macOS Command Line Tool project – so that it supports concurrency out of the box. This is one of those changes that might seem trivial on the surface, but took a lot of work to make happen.
In practice, it means you can write code like this directly into your main.swift files:
let url = URL(string: "https://hws.dev/readings.json")!
let (data, _) = try await URLSession.shared.data(from: url)
let readings = try JSONDecoder().decode([Double].self, from: data)
print("Found \(readings.count) temperature readings")Previously, we had to create a new @main struct that had an asynchronous main() method, so this new, simpler approach is a big improvement.
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Other changes in Swift 5.7…
- if let shorthand for unwrapping optionals
- Multi-statement closure type inference
- Clock, Instant, and Duration
- Regular expressions
- Type inference from default expressions
- Opaque parameter declarations
- Structural opaque result types
- Unlock existentials for all protocols
- Lightweight same-type requirements for primary associated types
- Constrained existential types
- Distributed actor isolation
- buildPartialBlock for result builders
- Implicitly opened existentials
- Swift snippets
- Unavailable from async attribute
Download all Swift 5.7 changes as a playground Link to Swift 5.7 changes
