Concurrency and streams

Task<Value>, await(), spawn, Channel, and the two ends of a stream, Source and Sink.

What belongs here#

Everything about waiting for a value and about moving values between tasks or across time: Task, spawn, await(), Channel, Source, Sink, and the Stage values a stream shares with an ordinary pipeline. What does not belong here: the lazy stages and collectors themselves, which are synchronous and live in collections-and-iteration/ - a stream reuses them rather than defining its own.

Pages#

• Tasks - Task is what an asynchronous function answers; await() waits for it and answers the value, and a cancellation is passed on to the waiter instead of answered.
• Channels - A Channel is a stream in memory whose one holder has both ends, handed out separately as a Source and a Sink so a producer never sees the reading end and a consumer never sees the writing one.
• Streams - Source and Sink are the asynchronous siblings of Iterator and Accumulator, with the same verbs, the same Stage values in between, and a failure that stands in the type on both ends.