7c79f05cd4
This PR improves the `Promise` API by considering how dropped promises can lead to never-finished tasks.
29 lines
590 B
Text
29 lines
590 B
Text
import Std.Sync.Channel
|
|
|
|
open IO
|
|
|
|
-- not in the run/ directory because then it would be run with -j0
|
|
|
|
#eval do
|
|
let promise ← Promise.new
|
|
promise.resolve 42
|
|
assert! promise.result?.get = some 42
|
|
|
|
|
|
/- Dropping a promise resolves `result?` to `none`. -/
|
|
#eval do
|
|
let promise : Promise Nat ← Promise.new
|
|
assert! promise.result?.get = none
|
|
|
|
#eval do
|
|
let ch ← Std.Channel.new
|
|
|
|
let out ← IO.mkRef #[]
|
|
ch.send 0
|
|
let drainFinished ← ch.forAsync fun x => out.modify (·.push x)
|
|
ch.send 1
|
|
ch.close
|
|
ch.send 2
|
|
|
|
IO.wait drainFinished
|
|
assert! (← out.get) = #[0, 1]
|