lachenmayer / asyncextensions

AsyncExtensions aims to mimic Swift Combine operators for async sequences.

AsyncExtensions

AsyncExtensions provides a collection of operators that intends to ease the creation and combination of AsyncSequences.

AsyncExtensions can be seen as a companion to Apple swift-async-algorithms, which provides operators that the community needs and are not provided by Apple.

Adding AsyncExtensions as a Dependency

To use the AsyncExtensions library in a SwiftPM project, add the following line to the dependencies in your Package.swift file:

.package(url: "https://github.com/sideeffect-io/AsyncExtensions"),

Include "AsyncExtensions" as a dependency for your executable target:

.target(name: "<target>", dependencies: ["AsyncExtensions"]),

Finally, add import AsyncExtensions to your source code.

Features

Channels

• AsyncBufferedChannel: Buffered communication channel between tasks. The elements are not shared and will be spread across consumers (same as AsyncStream)
• AsyncThrowingBufferedChannel: Throwing buffered communication channel between tasks

Subjects

• AsyncPassthroughSubject: Subject with a shared output
• AsyncThrowingPassthroughSubject: Throwing subject with a shared output
• AsyncCurrentValueSubject: Subject with a shared output. Maintain an replays its current value
• AsyncThrowingCurrentValueSubject: Throwing subject with a shared output. Maintain an replays its current value
• AsyncReplaySubject: Subject with a shared output. Maintain an replays a buffered amount of values
• AsyncThrowingReplaySubject: Throwing subject with a shared output. Maintain an replays a buffered amount of values

Combiners

• merge(_:): Merges any AsyncSequence into an AsyncSequence of elements
• withLatest(_:): Combines elements from self with the last known element from an other AsyncSequence
• withLatest(_:_:): Combines elements from self with the last known elements from two other async sequences

Creators

• AsyncEmptySequence: Creates an AsyncSequence that immediately finishes
• AsyncFailSequence: Creates an AsyncSequence that immediately fails
• AsyncJustSequence: Creates an AsyncSequence that emits an element an finishes
• AsyncThrowingJustSequence: Creates an AsyncSequence that emits an elements and finishes bases on a throwing closure
• AsyncTimerSequence: Creates an AsyncSequence that emits a date value periodically
• AsyncStream Pipe: Creates an AsyncStream and returns a tuple standing for its inputs and outputs

Operators

• handleEvents(): Executes closures during the lifecycle of the self
• mapToResult(): Maps elements and failure from self to a Result type
• prepend(_:): Prepends an element to self
• scan(_:_:): Transforms elements from self by providing the current element to a closure along with the last value returned by the closure
• assign(_:): Assigns elements from self to a property
• collect(_:): Iterate over elements from self and execute a closure
• eraseToAnyAsyncSequence(): Erases to AnyAsyncSequence
• flatMapLatest(_:): Transforms elements from self into a AsyncSequence and republishes elements sent by the most recently received AsyncSequence when self is an AsyncSequence of AsyncSequence
• multicast(_:): Shares values from self to several consumers thanks to a provided Subject
• share(): Shares values from self to several consumers
• switchToLatest(): Republishes elements sent by the most recently received AsyncSequence when self is an AsyncSequence of AsyncSequence

More operators and extensions are to come. Pull requests are of course welcome.