lean4-htt/Lake/Task.lean
2021-11-09 16:49:14 -05:00

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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 := ExceptT ε Task
-- # EIO Tasks
def EIOTask ε := ETask ε
instance : Monad (EIOTask ε) := inferInstanceAs <| Monad (ETask ε)
namespace EIOTask
def spawn (act : EIO ε α) (prio := Task.Priority.dedicated) : EIO ε (EIOTask ε α) :=
EIO.asTask act prio
instance : Async (EIO ε) (EIOTask ε) := ⟨spawn⟩
def await (self : EIOTask ε α) : EIO ε α := do
match (← IO.wait self) with
| Except.ok a => pure a
| Except.error e => throw e
instance : Await (EIOTask ε) (EIO ε) := ⟨await⟩
def mapAsync (f : α → EIO ε β) (self : EIOTask ε α) (prio := Task.Priority.dedicated) : EIO ε (EIOTask ε β) :=
EIO.mapTask (fun | Except.ok a => f a | Except.error e => throw e) self prio
instance : MapAsync (EIO ε) (EIOTask ε) := ⟨mapAsync⟩
def bindAsync (self : EIOTask ε α) (f : α → EIO ε (EIOTask ε β)) (prio := Task.Priority.dedicated) : EIO ε (EIOTask ε β) :=
EIO.bindTask self (fun | Except.ok a => f a | Except.error e => throw e) prio
instance : BindAsync (EIO ε) (EIOTask ε) := ⟨bindAsync⟩
def seqLeftAsync (self : EIOTask ε α) (act : EIO ε β) (prio := Task.Priority.dedicated) : EIO ε (EIOTask ε α) :=
self.mapAsync (fun a => do discard act; pure a) prio
instance : SeqLeftAsync (EIO ε) (EIOTask ε) := ⟨seqLeftAsync⟩
def seqRightAsync (self : EIOTask ε α) (act : EIO ε β) (prio := Task.Priority.dedicated) : EIO ε (EIOTask ε β) :=
self.mapAsync (fun _ => act) prio
instance : SeqRightAsync (EIO ε) (EIOTask ε) := ⟨seqRightAsync⟩
end EIOTask