data Reply a = Go a | StopThe scheduler's reply when it resumes a suspended fibre: Go v delivers the awaited value; Stop asks the fibre to CANCEL (it was cancelled by its scope).
importPour l'utiliser :
import ConcurStructured concurrency — the Concur effect
Synopsis
data Reply a = Go a | Stopawait : Fiber a -> a with Concuryield : () with Concurscope : (Group e -> a with Concur, Throw e) -> a with Concur, Throw econcurrently : (() -> a with Concur, Throw e) -> (() -> b with Concur, Throw e) -> (a, b) with Concur, Throw eparallel : List (() -> a with Concur, Throw e) -> List a with Concur, Throw erace : (() -> a with Concur, Throw e) -> (() -> a with Concur, Throw e) -> a with Concur, Throw ebracket : (() -> r with e) -> (r -> b with e) -> (r -> a with e) -> a with efinally : (() -> a with e) -> (() -> b with e) -> a with e
await : Fiber a -> a with ConcurSuspend the current fibre until fib resolves, yielding its value. If the current fibre is itself cancelled while waiting, it unwinds here instead.
yield : () with ConcurCooperative reschedule point — hand control to the scheduler (equity + a cancellation checkpoint).
scope : (Group e -> a with Concur, Throw e) -> a with Concur, Throw eA NURSERY (structured scope). Runs body with a fresh Group; children spawned into the group via spawnIn are OWNED by the scope. scope returns only once EVERY child has settled (no leak). If a child FAILS, the siblings are CANCELLED — each unwinding its brackets — and the error is re-raised in the parent. The child error type e flows through Group e to the re-raised throw e.
concurrently : (() -> a with Concur, Throw e) -> (() -> b with Concur, Throw e) -> (a, b) with Concur, Throw eRun two computations concurrently and return both results. If either fails, the other is cancelled and the error propagates.
parallel : List (() -> a with Concur, Throw e) -> List a with Concur, Throw eRun a list of computations concurrently and collect their results IN ORDER. If any fails, the rest are cancelled and the error propagates.
race : (() -> a with Concur, Throw e) -> (() -> a with Concur, Throw e) -> a with Concur, Throw eRace two computations: the FIRST to finish wins, the loser is CANCELLED. If the first to settle FAILS, the scope fails and its error propagates (the other is cancelled too).
bracket : (() -> r with e) -> (r -> b with e) -> (r -> a with e) -> a with ebracket acquire release use: acquire a resource, run use with it, and run release EXACTLY ONCE on every exit — normal completion, a throw, or a structured CANCELLATION.
finally : (() -> a with e) -> (() -> b with e) -> a with efinally action cleanup: run action, then run cleanup on every exit (normal, throw, or cancellation).