Swift Equatable and Comparable

How it works

Equatable supports ==, while Comparable adds a consistent ordering. Swift can synthesise equality for suitable stored properties, but a custom sort relation must agree with the value model. Hashable additionally supports sets and dictionary keys; equal values must hash consistently.

Run this Swift example

Install the toolchain for your platform from Swift.org, then check swift --version. The reviewed portable baseline is Swift 6.4.2 in Swift 6 mode on Ubuntu 26.04 x86_64 through the PC’s existing WSL installation. These are real Linux executions, not claims of Windows-native or Apple-platform test results. Windows Swift has separate C++/SDK prerequisites in its official setup guide.

Save the complete source as equatable-comparable.swift in a new learning folder. On Linux/macOS compile with swiftc -swift-version 6 -parse-as-library equatable-comparable.swift -o lesson, then run ./lesson. On a configured Windows toolchain use an output such as lesson.exe and run .\lesson.exe. The parse-as-library option supports the explicit @main entry point used by these sources. Compile each ordinary lesson separately.

Bhylu has no Swift browser runner. The JavaScript/Python editors do not run these sources; Apache, PHP and MySQL are not required. Downloads are source text, never executable teaching endpoints.

Download the complete equatable-comparable.swift · Download all source files with hash checks

For the optional collection, save download-examples.mjs in a new folder and run node download-examples.mjs. A local preview uses node download-examples.mjs http://127.0.0.1:8000/examples/swift/. It refuses an existing bhylu-swift-examples folder and installs or executes no Swift automatically. Apple-only files remain separate Xcode learning examples, not a portable Swift package target.

Example

struct Ticket: Equatable, Comparable {
    let number: Int
    static func < (left: Ticket, right: Ticket) -> Bool { left.number < right.number }
}

@main
struct Lesson {
    static func main() {
        let values = [Ticket(number: 42), Ticket(number: 18), Ticket(number: 31)]
        print(values.sorted().map { $0.number })
        print(Ticket(number: 18) == Ticket(number: 18))
    }
}

Expected result

[18, 31, 42]
true

Ordering compares the ticket number directly rather than subtracting two possibly large integers. Equality is synthesised from the one stored field. A real identity might include a workshop or date, so choose its fields deliberately.