lean4-htt/Lake/Task.lean

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/-
Copyright (c) 2021 Mac Malone. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Mac Malone
-/
import Lake.Async
namespace Lake
-- # Tasks
instance : Monad Task where
map := Task.map
pure := Task.pure
bind := Task.bind
abbrev ETask ε α := ExceptT ε Task α
-- # IO Tasks
def IOTask α := ETask IO.Error α
instance : Monad IOTask := inferInstanceAs <| Monad (ETask IO.Error)
namespace IOTask
def spawn (act : IO α) (prio := Task.Priority.dedicated) : IO (IOTask α) :=
IO.asTask act prio
def await (self : IOTask α) : IO α := do
IO.ofExcept (← IO.wait self)
def mapAsync (f : α → IO β) (self : IOTask α) (prio := Task.Priority.dedicated) : IO (IOTask β) :=
IO.mapTask (fun x => do let x ← IO.ofExcept x; f x) self prio
def andThen (self : IOTask α) (act : IO β) (prio := Task.Priority.dedicated) : IO (IOTask β) :=
IO.mapTask (fun x => IO.ofExcept x *> act) self prio
instance : HAndThen (IOTask α) (IO β) (IO (IOTask β)) := ⟨andThen⟩
def bindAsync (self : IOTask α) (f : α → IO (IOTask β)) (prio := Task.Priority.dedicated) : IO (IOTask β) :=
IO.bindTask self (fun x => do let x ← IO.ofExcept x; f x) prio
instance : MonadAsync IO IOTask where
async := IOTask.spawn
await := IOTask.await
mapAsync := IOTask.mapAsync
bindAsync := IOTask.bindAsync
end IOTask
section
variable [Monad m] [MonadAsync m n]
def afterTaskList (tasks : List (n α)) (act : m β) : m (n β) :=
afterListAsync (async act) tasks
def afterTaskArray (tasks : Array (n α)) (act : m β) : m (n β) :=
afterArrayAsync (async act) tasks
end
instance : HAndThen (List (IOTask α)) (IO β) (IO (IOTask β)) := ⟨afterTaskList⟩
instance : HAndThen (Array (IOTask α)) (IO β) (IO (IOTask β)) := ⟨afterTaskArray⟩