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This release is all about performance and quality of life improvements.

Ergonomic Improvements

• Supercharged flatMap. Add variants which allow combinations of Future<T, E>.flatMap { Future<T, Never> } and Future<T, Never>.flatMap { Future<T, E> }
• Instead of a convoluted on(scheduler:success:failure:completion:) method to change a scheduler you now call a separate observe(on scheduler:) or observe(on queue:) (new!) method before attaching callbacks. The observe(on:) methods are almost instanteneous thanks to the fact that Future is a struct now.
• Creating promises is now simpler: Promise<Int, Error>() instead of Future<Int, Error>.promise
• Future(value: 1) now compiles and automatically infers type to be Future<Int, Never>
• Rename attemptMap to tryMap, implement tryMap in terms of flatMap
• Remove ignoreError, materialize is a better alternative
• Attaching two callbacks via the same on would result in these callbacks called on the same run of run loop on the selected queue/scheduler
• Add convenience Future.init(result:), Promise.resolve(result:)
• Implement CancellationTokenSource using Future, simpler implementation

Performance Improvements

• Future is a struct now. Future(value:) and Future(error:) are now 2.5x times faster
• Optimize the way internal Promise handlers are managed - it's just one array instead of two now, attaching callbacks 30% faster, resolve 30% faster
• Slightly increase the performance of all composition functions (by using observe directly)
• Resolving promises concurrently from multiple threads is now up to 5x times faster

• Remove Scheduler enum, it's a simple function now. See Threading for more info.
• Add Swift Package Manager support
• Update README.md

FutureCocoa

• Make FutureCocoa available on macOS, watchOS and tvOS
• Add FutureCocoa README.md
• Add NSObject.fx.deallocated

• Fix module name in FutureX.podspec

FutureX is a completely new beast. It has a new name and it a new goal - to provide the best future implementation in Swift.

Future

There are a lot of improvements in the core part of the frameworks:

• Add custom Scheduler instead of DispatchQueue. By default the callbacks are now run with .main(immediate: true) strategy. It runs immediately if on the main thread, otherwise asynchronously on the main thread. The rationale is provided in README.
• Method on now returns self so that you can continue the chain. The returned result is marked as discardable.
• Promise is now nested in Future<Value, Error> like other types like Result. To create a promise call Future<Value, Error>.promise.
• Move zip, reduce to extension Future where Value == Any, Error == Any so that Future would be a simple namespace (inspired by RxSwift)
• Remove isPending
• Make Future<Value, Error>.Result Equatable
• Rewrite README

Future Additions

There are also lots of bonus additions:

• first
• after: Returns a future which succeeds after a given time interval.
• retry
• castError
• ignoreError
• materialize that uses built-in Never to indicate that the error is not possible
• castError
• mapThrowing

CancellationToken

FutureX now ships with a CancellationToken implementation. See rational in README.

FutureCocoa

An initial version of Future extensions for native frameworks.

• Documentation improvements

• Add wait method that blocks the current thread and waits until the future receives a result
• Make Future.Result type public
• Pass result in the completion

• map and mapError now no longer require intermediate Future instance to be created, increased performance by up to 40%.
• map, flatMap, mapError, flatMapError now run on the queue on which the future was resolved. It increases the performance of a typical chain by up to 3 times and also simplifies debugging - there are less queue.async operations being performed.
• Remove observeOn. It was introducing unwanted state in Future. To observe success/failure on a different queue use a new queue parameter (DispatchQueue.main by default) of on method.

• Add zip with three futures as arguments

Pill 0.6 is a complete reimagining of the library. See a post for an overview of the changes.

• Add typed errors - Future<Value, Error>, Promise<Value, Error>
• Adopt functional Swift naming: map, flatMap instead of then
• Add new methods: zip, reduce
• Add observeOn method to observe changes on differnet dispatch queues
• Fix an issue where then/catch callbacks could be executed in a different from registration order
• Remove throws support (not type-safe)