Swift Delta

Swift Delta is a package for a type Delta<Element> with three cases:

• source(Element)
• target(Element)
• transition(source: Element, target: Element)

• Documentation
• Swift Package Index

This Delta type represents an inclusive OR relation: Either a source element is available, or a target element is available, or both are available. Delta behaves similar to Optional, but instead of representing 0 or 1 elements, it represents 1 or 2 elements.

The source and target are described as the two sides of a delta. Both sides are accessible via optional source and target properties. Convenient methods like resolve(favoring:) and merge(coalesce:) also provide access to the elements.

Transform a Delta value to a different Delta value using map(:), asyncMap(:), mapAny(:), or mapAll(:).

The Delta type also conforms to all standard protocols (depending on the conformances of it’s Element type):

• Equatable
• Hashable
• CustomDebugStringConvertible
• Encodable
• EncodableWithConfiguration
• Decodable
• DecodableWithConfiguration
• Sendable
• BitwiseCopyable
• ~Copyable

Additionally, Delta conforms to RandomAccessCollection, allowing for iteration over the elements and many other operations provided by Sequence, Collection, and BidirectionalCollection.

Add swift-delta as a dependency to your package:

let package = Package(
    // ...
    dependencies: [
        .package(url: "https://github.com/Formkunft/swift-delta.git", .upToNextMajor(from: "0.5.1")),
    ],
    targets: [
        .target(
            // ...
            dependencies: [
                .product(name: "DeltaModule", package: "swift-delta"),
            ]),
    ]
)

Then, import DeltaModule in your code:

import DeltaModule

// ...