---
title: swift-primitives/swift-equation-primitives
framework: Swift Package Catalog
role: article
path: packages/swift-primitives/swift-equation-primitives
---

# swift-primitives/swift-equation-primitives

`Equation.Protocol` — equality with `borrowing` parameters, so `~Copyable` types can compare for equality without being copied. Mirrors `Swift.Equatable` and, on Swift 6.4 and later, *is* `Swift.Equatable` via a namespace typealias once [SE-0499](https://github.com/swiftlang/swif

## Key Features

- **Move-only equality** — `static func == (lhs: borrowing Self, rhs: borrowing Self) -> Bool` lets `~Copyable` types compare equal without being consumed. - **SE-0499 dual-mode** — Under Swift <6.4, the package ships its own protocol fork. Under Swift 6.4+, the protocol is a typealias to `Swift.Equatable`. Conformances written today work on both compiler families. - **Stdlib bridges included** — Standard Library Integration target re-conforms common stdlib types (`Int`, `String`, `[T]`, `Optional`, `Range`, …) under Swift <6.4, so Swift `Equatable` types are also `Equation.Protocol` types with no per-call-site work. - **Default `!=`** — Implement `==`; `!=` comes from the protocol's default extension.

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## Quick Start

A move-only token type conforms in two lines:

```swift import Equation_Primitives

struct Token: ~Copyable {     let id: Int }

extension Token: Equation.`Protocol` {     static func == (lhs: borrowing Token, rhs: borrowing Token) -> Bool {         lhs.id == rhs.id     } }

let a = Token(id: 1) let b = Token(id: 1) let c = Token(id: 2)

let equal: Bool = a == b      // true let notEqual: Bool = a != c   // true (default impl from the protocol) ```

A `Copyable` type that already conforms to `Swift.Equatable` conforms with an empty extension — the existing `==` satisfies the requirement:

```swift struct UserID: Equatable, Equation.`Protocol` {     let value: UInt64 } // no body required — Swift.Equatable's `==` satisfies the requirement ```

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## Installation

Add the dependency to your `Package.swift`:

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

Add the umbrella product to your target (re-exports the protocol and the stdlib bridges):

```swift .target(     name: "App",     dependencies: [         .product(name: "Equation Primitives", package: "swift-equation-primitives")     ] ) ```

For narrower surface, depend on `Equation Primitives Core` alone (protocol only, no stdlib bridges).

Requires Swift 6.3.1 and macOS 26 / iOS 26 / tvOS 26 / watchOS 26 / visionOS 26 (or the corresponding Linux / Windows toolchain).

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## Architecture

Three library products plus a Test Support target:

| Product | Contents | When to import | |---------|----------|----------------| | `Equation Primitives` | Umbrella — re-exports Core + Standard Library Integration | Most consumers | | `Equation Primitives Core` | `Equation` namespace + `Equation.Protocol` | Embedded contexts, or when stdlib bridges are unwanted | | `Equation Primitives Standard Library Integration` | Re-conformance of stdlib types under Swift <6.4 | Pulled in transitively by the umbrella | | `Equation Primitives Test Support` | Re-export of `Tagged Primitives Test Support` | Test target only |

The `Standard Library Integration` target's bridges are gated behind `#if swift(<6.4)`. Under Swift 6.4 and later, stdlib types already conform to `Swift.Equatable` (which `Equation.Protocol` typealiases to) and the bridges become no-ops.

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## Stability

Pre-1.0. The protocol surface is intentionally small: one method (`==`), one default (`!=`), one namespace (`Equation`). The expected long-term shape is full retirement of the namespace once the ecosystem's minimum Swift version reaches 6.4 stable, at which point consumers use `Swift.Equatable` directly. The `0.1.0` tag commits to source compatibility for the dual-mode bridge until that retirement is staged.

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## Platform Support

| Platform         | CI  | Status       | |------------------|-----|--------------| | macOS 26         | Yes | Full support | | Linux            | Yes | Full support | | Windows          | Yes | Full support | | iOS/tvOS/watchOS | —   | Supported    | | Swift Embedded   | —   | Supported    |

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## Related Packages

- [`swift-comparison-primitives`](https://github.com/swift-primitives/swift-comparison-primitives) — three-way comparison + `Comparison.Protocol` (refines `Equation.Protocol`). - [`swift-hash-primitives`](https://github.com/swift-primitives/swift-hash-primitives) — typed hash output + `Hash.Protocol` (refines `Equation.Protocol`). - [`swift-tagged-primitives`](https://github.com/swift-primitives/swift-tagged-primitives) — phantom-typed value wrappers; `Tagged` conditionally conforms to `Equation.Protocol`. - [`swift-property-primitives`](https://github.com/swift-primitives/swift-property-primitives) — fluent accessor namespaces.

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## License

Apache 2.0. See [LICENSE.md](LICENSE.md).

## Package Metadata

Repository: swift-primitives/swift-equation-primitives

Default branch: main

README: README.md