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. For now there is an overlap between both libraries, but when swift-async-algorithms becomes stable the overlapping operators while be deprecated in AsyncExtensions. Nevertheless AsyncExtensions will continue to provide the 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

zip(_:_:): Zips two AsyncSequence into an AsyncSequence of tuple of elements
zip(_:_:_:): Zips three AsyncSequence into an AsyncSequence of tuple of elements
zip(_:): Zips any async sequences into an array of elements
merge(_:_:): Merges two AsyncSequence into an AsyncSequence of elements
merge(_:_:_:): Merges three AsyncSequence into an AsyncSequence of elements
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
AsyncLazySequence: Creates an AsyncSequence of the elements from the base sequence
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 Suject
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.

davdroman/AsyncExtensions