dd7ca772d8
This PR extends `Std.Channel` to provide a full sync and async API, as well as unbounded, zero sized and bounded channels. A few notes on the implementation: - the bounded channel is inspired by [Go channels on steroids](https://docs.google.com/document/d/1yIAYmbvL3JxOKOjuCyon7JhW4cSv1wy5hC0ApeGMV9s/pub) though currently doesn't do any of the lock-free optimizations - @mhuisi convinced me that having a non-closable channel may be a good idea as this alleviates the need for error handling which is very annoying when working with `Task`. This does complicate the API a little bit and I'm not quite sure whether this is a choice we want users to give. An alternative to this would be to just write `send!` that panics on sending to a closed channel (receiving from a closed channel is not an error), this is for example the behavior that golang goes with.
29 lines
681 B
Text
29 lines
681 B
Text
import Std.Sync.Channel
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open IO
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-- not in the run/ directory because then it would be run with -j0
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#eval do
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let promise ← Promise.new
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promise.resolve 42
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assert! promise.result?.get = some 42
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/- Dropping a promise resolves `result?` to `none`. -/
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#eval do
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let promise : Promise Nat ← Promise.new
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assert! promise.result?.get = none
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#eval show IO _ from do
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let ch ← Std.CloseableChannel.new
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let out ← IO.mkRef #[]
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ch.sync.send 0
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let drainFinished ← ch.forAsync fun x => out.modify (·.push x)
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ch.sync.send 1
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ch.close
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assert! (← EIO.toBaseIO (ch.sync.send 2)) matches .error .closed
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IO.wait drainFinished
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assert! (← out.get) = #[0, 1]
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