Single Iterator Primitives

The iterator-domain face of Single: conforms the one-element container to Iterable, vending a single-shot Once as its iterator.

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Quick Start

Single holds exactly one element. Importing this package conforms it to Iterable, so the one-element container participates in iterator-generic code — it yields its element exactly once, then ends.

import Single_Iterator_Primitives

// `Single` holds exactly one element. This package adds the `Iterable` conformance.
let single = Single(42)

// Iterate it like any other Iterable — it yields its element exactly once.
single.forEach { print($0) }   // 42

// `makeIterator()` only borrows the container, so it stays multipass.
var collected: [Int] = []
single.forEach { collected.append($0) }
single.forEach { collected.append($0) }
print(collected)   // [42, 42]

The conformance requires Element: Copyable, because makeIterator() only borrows the container and must copy the element into the owned Iterator.Once. Move-only / borrowing iteration of a Single is a separate, collection-domain concern.

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Installation

dependencies: [
    .package(url: "https://github.com/swift-primitives/swift-single-iterator-primitives.git", branch: "main")
]

.target(
    name: "App",
    dependencies: [
        .product(name: "Single Iterator Primitives", package: "swift-single-iterator-primitives"),
    ]
)

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Architecture

One library product. It declares no types of its own — only the retroactive conformance bridging swift-single-primitives (the Single container) to swift-iterator-primitives (Iterable and Iterator.Once).

Product	Target	Purpose
Single Iterator Primitives	Sources/Single Iterator Primitives/	The retroactive Single: Iterable conformance and its Iterator typealias — Iterator.Once wrapped in the span-materializing adapter.

Foundation-free.

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Platform Support

Platform	Status
macOS 26	Full support
Linux	Full support
Windows	Full support
iOS / tvOS / watchOS / visionOS	Supported

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Community

License

Apache 2.0. See LICENSE.md.