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Swift Warts

Briefs about unfortunate pain points in the Swift language and standard library

Definition Order Matters in Swift Packages

You Can Use Helpers in Package.swift, but only if they are defined before use.
Lack of a decltype Equivalent

In the absence of a decltype-like mechanism, some nice-to-have macros wind up unimplementable
You Cannot Express Generic Actor Isolation Parameters

Swift lets you write @MainActor and @SomeOtherActor, but not @'A, where A is a generic actor parameter.
Lazy Sequences Lack Primary Associated Types

You can write Sequence<Element> but not LazySequenceProtocol<Element>
Lazy Sequences Lack Primary Associated Types

You can write Sequence<Element> but not LazySequenceProtocol<Element>
Name Collisions in Result Builders

You get a ForEach, and you get a ForEach, and...
First Trailing Closure Cannot Have a Label

Swift forbids labeling the first trailing closure, which can be a surprising obstacle to idiomatic API design.
Lazy Sequences "Decay" Easily

Swift's lazy functional API is elegant, but prone to silently decaying back to its eager equivalent.