diff --git a/CHANGELOG.md b/CHANGELOG.md --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -1,10 +1,14 @@ # Revsion history of io-classes -## next release +## 1.4.0.0 ### Breaking changes +* Removed deprecated module `Control.Monad.Class.MonadVar`. + ### Non-breaking changes + +* Fixed some module haddock typos. ## 1.3.1.0 diff --git a/NOTICE b/NOTICE --- a/NOTICE +++ b/NOTICE @@ -1,4 +1,4 @@ -Copyright 2019-2023 Input Output Global Inc (IOG) +Copyright 2019-2024 Input Output Global Inc (IOG) Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. diff --git a/README.md b/README.md --- a/README.md +++ b/README.md @@ -80,7 +80,38 @@ * [MonadST]: provides a way to lift `ST`-computations. * [MonadSay]: dummy debugging interface +## Differences from `base`, `async`, or `exceptions` packages +### Major differences + +* `getMonotonicTime` returns `Time` (a newtype wrapper around `DiffTime`) +* `Deadlock` exceptions are not thrown to the main thread (see + [ref][io-deadlock]), so they cannot be caught. This was a design decision, + which allows to catch all deadlocks which otherwise could be captured by + a `catch`. + +### Minor differences + +Some of the types have more general kind signatures, e.g. + +``` +type Async :: (Type -> Type) -> Type -> Type +``` + +The first type of kind `Type -> Type` describes the monad which could be +instantiated to `IO`, `IOSim` or some other monad stacks built with monad +transformers. The same applies to many other types, e.g. `TVar`, `TMVar`. + +The following types although similar to the originals are not the same as the +ones that come from `base`, `async`, or `exceptions` packages: + +* `Handler` (origin: `base`) +* `MaskingState` (origin: `base`) +* `Concurrently` (origin: `async`) +* `ExceptionInLinkedThread` (origin: `async`): `io-class`es version does not + store `Async` +* `ExitCase` (origin: `exceptions`) + ## Debuging & Insepction We provide quite extended debugging & inspection API. This proved to be @@ -117,6 +148,7 @@ [contributing]: https://www.github.com/input-output-hk/io-sim/tree/master/CONTRIBUTING.md [`nothunks`]: https://hackage.haskell.org/package/nothunks [labelThread-base]: https://hackage.haskell.org/package/base-4.17.0.0/docs/GHC-Conc-Sync.html#v:labelThread +[io-deadlock]: https://hackage.haskell.org/package/base-4.19.0.0/docs/Control-Exception.html#t:Deadlock [MonadEventlog]: https://hackage.haskell.org/package/io-sim-classes/docs/Control-Monad-Class-MonadEventlog.html#t:MonadEventlog [Debug.Trace]: https://hackage.haskell.org/package/base/docs/Debug-Trace.html diff --git a/io-classes.cabal b/io-classes.cabal --- a/io-classes.cabal +++ b/io-classes.cabal @@ -1,14 +1,18 @@ cabal-version: 3.0 name: io-classes -version: 1.3.1.0 +version: 1.4.0.0 synopsis: Type classes for concurrency with STM, ST and timing description: IO Monad class hierarchy compatible with - [io-sim](https://hackage.haskell.org/package/io-sim), 'base', 'async', - 'stm', 'exceptions' & 'time' packages. + [io-sim](https://hackage.haskell.org/package/io-sim), + [base](https://hackage.haskell.org/package/base), + [async](https://hackage.haskell.org/package/async), + [stm](https://hackage.haskell.org/package/stm), + [exceptions](https://hackage.haskell.org/package/exceptions) & + [time](https://hackage.haskell.org/package/time) packages. license: Apache-2.0 license-files: LICENSE NOTICE -copyright: 2019-2023 Input Output Global Inc (IOG) +copyright: 2019-2024 Input Output Global Inc (IOG) author: Alexander Vieth, Duncan Coutts, Marcin Szamotulski, Thomas Winant maintainer: Duncan Coutts duncan@well-typed.com, Marcin Szamotulski coot@coot.me category: Control @@ -56,7 +60,6 @@ Control.Monad.Class.MonadAsync Control.Monad.Class.MonadEventlog Control.Monad.Class.MonadFork - Control.Monad.Class.MonadMVar Control.Monad.Class.MonadSay Control.Monad.Class.MonadST Control.Monad.Class.MonadSTM @@ -66,6 +69,7 @@ Control.Monad.Class.MonadTimer Control.Monad.Class.MonadTest default-language: Haskell2010 + default-extensions: ImportQualifiedPost other-extensions: CPP DataKinds DefaultSignatures diff --git a/src/Control/Concurrent/Class/MonadMVar.hs b/src/Control/Concurrent/Class/MonadMVar.hs --- a/src/Control/Concurrent/Class/MonadMVar.hs +++ b/src/Control/Concurrent/Class/MonadMVar.hs @@ -8,13 +8,13 @@ , MonadInspectMVar (..) ) where -import qualified Control.Concurrent.MVar as IO -import Control.Monad.Class.MonadThrow +import Control.Concurrent.MVar qualified as IO +import Control.Monad.Class.MonadThrow -import Control.Monad.Reader (ReaderT (..)) -import Control.Monad.Trans (lift) +import Control.Monad.Reader (ReaderT (..)) +import Control.Monad.Trans (lift) -import Data.Kind (Type) +import Data.Kind (Type) class Monad m => MonadMVar m where diff --git a/src/Control/Concurrent/Class/MonadSTM.hs b/src/Control/Concurrent/Class/MonadSTM.hs --- a/src/Control/Concurrent/Class/MonadSTM.hs +++ b/src/Control/Concurrent/Class/MonadSTM.hs @@ -4,11 +4,11 @@ (module STM) where -import Control.Monad.Class.MonadSTM as STM -import Control.Concurrent.Class.MonadSTM.TVar as STM -import Control.Concurrent.Class.MonadSTM.TMVar as STM -import Control.Concurrent.Class.MonadSTM.TChan as STM -import Control.Concurrent.Class.MonadSTM.TQueue as STM -import Control.Concurrent.Class.MonadSTM.TBQueue as STM -import Control.Concurrent.Class.MonadSTM.TArray as STM +import Control.Monad.Class.MonadSTM as STM +import Control.Concurrent.Class.MonadSTM.TVar as STM +import Control.Concurrent.Class.MonadSTM.TMVar as STM +import Control.Concurrent.Class.MonadSTM.TChan as STM +import Control.Concurrent.Class.MonadSTM.TQueue as STM +import Control.Concurrent.Class.MonadSTM.TBQueue as STM +import Control.Concurrent.Class.MonadSTM.TArray as STM diff --git a/src/Control/Concurrent/Class/MonadSTM/TArray.hs b/src/Control/Concurrent/Class/MonadSTM/TArray.hs --- a/src/Control/Concurrent/Class/MonadSTM/TArray.hs +++ b/src/Control/Concurrent/Class/MonadSTM/TArray.hs @@ -4,4 +4,4 @@ -- module Control.Concurrent.Class.MonadSTM.TArray (type TArray) where -import Control.Monad.Class.MonadSTM.Internal +import Control.Monad.Class.MonadSTM.Internal diff --git a/src/Control/Concurrent/Class/MonadSTM/TBQueue.hs b/src/Control/Concurrent/Class/MonadSTM/TBQueue.hs --- a/src/Control/Concurrent/Class/MonadSTM/TBQueue.hs +++ b/src/Control/Concurrent/Class/MonadSTM/TBQueue.hs @@ -25,4 +25,4 @@ , traceTBQueueIO ) where -import Control.Monad.Class.MonadSTM.Internal +import Control.Monad.Class.MonadSTM.Internal diff --git a/src/Control/Concurrent/Class/MonadSTM/TChan.hs b/src/Control/Concurrent/Class/MonadSTM/TChan.hs --- a/src/Control/Concurrent/Class/MonadSTM/TChan.hs +++ b/src/Control/Concurrent/Class/MonadSTM/TChan.hs @@ -23,4 +23,4 @@ , isEmptyTChan ) where -import Control.Monad.Class.MonadSTM.Internal +import Control.Monad.Class.MonadSTM.Internal diff --git a/src/Control/Concurrent/Class/MonadSTM/TMVar.hs b/src/Control/Concurrent/Class/MonadSTM/TMVar.hs --- a/src/Control/Concurrent/Class/MonadSTM/TMVar.hs +++ b/src/Control/Concurrent/Class/MonadSTM/TMVar.hs @@ -25,4 +25,4 @@ , traceTMVarIO ) where -import Control.Monad.Class.MonadSTM.Internal +import Control.Monad.Class.MonadSTM.Internal diff --git a/src/Control/Concurrent/Class/MonadSTM/TQueue.hs b/src/Control/Concurrent/Class/MonadSTM/TQueue.hs --- a/src/Control/Concurrent/Class/MonadSTM/TQueue.hs +++ b/src/Control/Concurrent/Class/MonadSTM/TQueue.hs @@ -1,6 +1,6 @@ {-# LANGUAGE ExplicitNamespaces #-} --- | This module corresponds to `Control.Concurrnet.STM.TVar` in "stm" package +-- | This module corresponds to `Control.Concurrent.STM.TQueue` in "stm" package -- module Control.Concurrent.Class.MonadSTM.TQueue ( -- * MonadSTM @@ -23,4 +23,4 @@ , traceTQueueIO ) where -import Control.Monad.Class.MonadSTM.Internal +import Control.Monad.Class.MonadSTM.Internal diff --git a/src/Control/Concurrent/Class/MonadSTM/TSem.hs b/src/Control/Concurrent/Class/MonadSTM/TSem.hs --- a/src/Control/Concurrent/Class/MonadSTM/TSem.hs +++ b/src/Control/Concurrent/Class/MonadSTM/TSem.hs @@ -17,4 +17,4 @@ , traceTSemIO ) where -import Control.Monad.Class.MonadSTM.Internal +import Control.Monad.Class.MonadSTM.Internal diff --git a/src/Control/Concurrent/Class/MonadSTM/TVar.hs b/src/Control/Concurrent/Class/MonadSTM/TVar.hs --- a/src/Control/Concurrent/Class/MonadSTM/TVar.hs +++ b/src/Control/Concurrent/Class/MonadSTM/TVar.hs @@ -23,4 +23,4 @@ , traceTVarIO ) where -import Control.Monad.Class.MonadSTM.Internal +import Control.Monad.Class.MonadSTM.Internal diff --git a/src/Control/Monad/Class/MonadAsync.hs b/src/Control/Monad/Class/MonadAsync.hs --- a/src/Control/Monad/Class/MonadAsync.hs +++ b/src/Control/Monad/Class/MonadAsync.hs @@ -10,6 +10,10 @@ {-# LANGUAGE TypeFamilyDependencies #-} -- MonadAsync's ReaderT instance is undecidable. {-# LANGUAGE UndecidableInstances #-} + +-- | API compatible with both +-- 'IO' and . +-- module Control.Monad.Class.MonadAsync ( MonadAsync (..) , AsyncCancelled (..) @@ -27,30 +31,30 @@ , Concurrently (..) ) where -import Prelude hiding (read) +import Prelude hiding (read) #if MIN_VERSION_base(4,18,0) -import Control.Applicative (Alternative (..)) +import Control.Applicative (Alternative (..)) #else -import Control.Applicative (Alternative (..), liftA2) +import Control.Applicative (Alternative (..), liftA2) #endif -import Control.Monad (forever) -import Control.Monad.Class.MonadFork -import Control.Monad.Class.MonadSTM -import Control.Monad.Class.MonadThrow -import Control.Monad.Class.MonadTimer +import Control.Monad (forever) +import Control.Monad.Class.MonadFork +import Control.Monad.Class.MonadSTM +import Control.Monad.Class.MonadThrow +import Control.Monad.Class.MonadTimer -import Control.Monad.Reader (ReaderT (..)) -import Control.Monad.Trans (lift) +import Control.Monad.Reader (ReaderT (..)) +import Control.Monad.Trans (lift) -import Control.Concurrent.Async (AsyncCancelled (..)) -import qualified Control.Concurrent.Async as Async -import qualified Control.Exception as E +import Control.Concurrent.Async (AsyncCancelled (..)) +import Control.Concurrent.Async qualified as Async +import Control.Exception qualified as E -import Data.Bifunctor (first) -import Data.Foldable (fold) -import Data.Functor (void) -import Data.Kind (Type) +import Data.Bifunctor (first) +import Data.Foldable (fold) +import Data.Functor (void) +import Data.Kind (Type) class ( MonadSTM m , MonadThread m diff --git a/src/Control/Monad/Class/MonadEventlog.hs b/src/Control/Monad/Class/MonadEventlog.hs --- a/src/Control/Monad/Class/MonadEventlog.hs +++ b/src/Control/Monad/Class/MonadEventlog.hs @@ -1,10 +1,8 @@ -module Control.Monad.Class.MonadEventlog - ( MonadEventlog (..) - ) where +module Control.Monad.Class.MonadEventlog (MonadEventlog (..)) where -import Control.Monad.Reader +import Control.Monad.Reader -import qualified Debug.Trace as IO (traceEventIO, traceMarkerIO) +import Debug.Trace qualified as IO (traceEventIO, traceMarkerIO) class Monad m => MonadEventlog m where diff --git a/src/Control/Monad/Class/MonadFork.hs b/src/Control/Monad/Class/MonadFork.hs --- a/src/Control/Monad/Class/MonadFork.hs +++ b/src/Control/Monad/Class/MonadFork.hs @@ -3,17 +3,22 @@ {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} +-- | A generalisation of +-- +-- API to both 'IO' and . +-- module Control.Monad.Class.MonadFork ( MonadThread (..) , labelThisThread , MonadFork (..) ) where -import qualified Control.Concurrent as IO -import Control.Exception (AsyncException (ThreadKilled), Exception, SomeException) -import Control.Monad.Reader (ReaderT (..), lift) -import Data.Kind (Type) -import qualified GHC.Conc.Sync as IO (labelThread) +import Control.Concurrent qualified as IO +import Control.Exception (AsyncException (ThreadKilled), Exception, + SomeException) +import Control.Monad.Reader (ReaderT (..), lift) +import Data.Kind (Type) +import GHC.Conc.Sync qualified as IO (labelThread) class (Monad m, Eq (ThreadId m), diff --git a/src/Control/Monad/Class/MonadMVar.hs b/src/Control/Monad/Class/MonadMVar.hs deleted file mode 100644 --- a/src/Control/Monad/Class/MonadMVar.hs +++ /dev/null @@ -1,3 +0,0 @@ -module Control.Monad.Class.MonadMVar {-# DEPRECATED "Use Control.Concurrent.Class.MonadMVar" #-} (module X) where - -import Control.Concurrent.Class.MonadMVar as X diff --git a/src/Control/Monad/Class/MonadST.hs b/src/Control/Monad/Class/MonadST.hs --- a/src/Control/Monad/Class/MonadST.hs +++ b/src/Control/Monad/Class/MonadST.hs @@ -1,9 +1,9 @@ {-# LANGUAGE RankNTypes #-} module Control.Monad.Class.MonadST (MonadST (..)) where -import Control.Monad.Reader +import Control.Monad.Reader -import Control.Monad.ST (ST, stToIO) +import Control.Monad.ST (ST, stToIO) -- | This class is for abstracting over 'stToIO' which allows running 'ST' diff --git a/src/Control/Monad/Class/MonadSTM.hs b/src/Control/Monad/Class/MonadSTM.hs --- a/src/Control/Monad/Class/MonadSTM.hs +++ b/src/Control/Monad/Class/MonadSTM.hs @@ -1,15 +1,15 @@ -- | This module corresponds to "Control.Monad.STM" in "stm" package -- -{-# LANGUAGE DataKinds #-} -{-# LANGUAGE DerivingStrategies #-} -{-# LANGUAGE FlexibleContexts #-} -{-# LANGUAGE GADTs #-} -{-# LANGUAGE MultiParamTypeClasses #-} -{-# LANGUAGE RankNTypes #-} -{-# LANGUAGE ScopedTypeVariables #-} +{-# LANGUAGE DataKinds #-} +{-# LANGUAGE DerivingStrategies #-} +{-# LANGUAGE FlexibleContexts #-} +{-# LANGUAGE GADTs #-} +{-# LANGUAGE MultiParamTypeClasses #-} +{-# LANGUAGE RankNTypes #-} +{-# LANGUAGE ScopedTypeVariables #-} -- undecidable instances needed for 'WrappedSTM' instances of 'MonadThrow' and -- 'MonadCatch' type classes. -{-# LANGUAGE UndecidableInstances #-} +{-# LANGUAGE UndecidableInstances #-} module Control.Monad.Class.MonadSTM ( MonadSTM (STM, atomically, retry, orElse, check) , throwSTM @@ -22,7 +22,7 @@ , MonadInspectSTM (..) ) where -import Control.Monad.Class.MonadSTM.Internal +import Control.Monad.Class.MonadSTM.Internal -- $non-standard-extensions -- diff --git a/src/Control/Monad/Class/MonadSTM/Internal.hs b/src/Control/Monad/Class/MonadSTM/Internal.hs --- a/src/Control/Monad/Class/MonadSTM/Internal.hs +++ b/src/Control/Monad/Class/MonadSTM/Internal.hs @@ -48,7 +48,7 @@ , isEmptyTMVarDefault , labelTMVarDefault , traceTMVarDefault - -- ** Default 'TBQueue' implementation + -- ** Default 'TQueue' implementation , TQueueDefault (..) , newTQueueDefault , writeTQueueDefault @@ -99,35 +99,35 @@ , labelTChanDefault ) where -import Prelude hiding (read) +import Prelude hiding (read) -import qualified Control.Concurrent.STM.TArray as STM -import qualified Control.Concurrent.STM.TBQueue as STM -import qualified Control.Concurrent.STM.TChan as STM -import qualified Control.Concurrent.STM.TMVar as STM -import qualified Control.Concurrent.STM.TQueue as STM -import qualified Control.Concurrent.STM.TSem as STM -import qualified Control.Concurrent.STM.TVar as STM -import Control.Monad (unless, when) -import qualified Control.Monad.STM as STM +import Control.Concurrent.STM.TArray qualified as STM +import Control.Concurrent.STM.TBQueue qualified as STM +import Control.Concurrent.STM.TChan qualified as STM +import Control.Concurrent.STM.TMVar qualified as STM +import Control.Concurrent.STM.TQueue qualified as STM +import Control.Concurrent.STM.TSem qualified as STM +import Control.Concurrent.STM.TVar qualified as STM +import Control.Monad (unless, when) +import Control.Monad.STM qualified as STM -import Control.Monad.Reader (ReaderT (..)) -import Control.Monad.Trans (lift) +import Control.Monad.Reader (ReaderT (..)) +import Control.Monad.Trans (lift) -import qualified Control.Monad.Class.MonadThrow as MonadThrow +import Control.Monad.Class.MonadThrow qualified as MonadThrow -import Control.Exception -import Data.Array (Array, bounds) -import qualified Data.Array as Array -import Data.Array.Base (IArray (numElements), MArray (..), - arrEleBottom, listArray, unsafeAt) -import Data.Foldable (traverse_) -import Data.Ix (Ix, rangeSize) -import Data.Kind (Type) -import Data.Proxy (Proxy (..)) -import Data.Typeable (Typeable) -import GHC.Stack -import Numeric.Natural (Natural) +import Control.Exception +import Data.Array (Array, bounds) +import Data.Array qualified as Array +import Data.Array.Base (IArray (numElements), MArray (..), arrEleBottom, + listArray, unsafeAt) +import Data.Foldable (traverse_) +import Data.Ix (Ix, rangeSize) +import Data.Kind (Type) +import Data.Proxy (Proxy (..)) +import Data.Typeable (Typeable) +import GHC.Stack +import Numeric.Natural (Natural) -- $default-implementations @@ -436,7 +436,7 @@ -- This is supported by 'IOSim' (and 'IOSimPOR'); 'IO' has a trivial instance. -- -- The simplest example is: - -- + -- -- > -- > traceTVar (Proxy @m) tvar (\_ -> TraceString . show) -- > diff --git a/src/Control/Monad/Class/MonadSay.hs b/src/Control/Monad/Class/MonadSay.hs --- a/src/Control/Monad/Class/MonadSay.hs +++ b/src/Control/Monad/Class/MonadSay.hs @@ -1,7 +1,7 @@ module Control.Monad.Class.MonadSay where -import Control.Monad.Reader -import qualified Data.ByteString.Char8 as BSC +import Control.Monad.Reader +import Data.ByteString.Char8 qualified as BSC class Monad m => MonadSay m where say :: String -> m () diff --git a/src/Control/Monad/Class/MonadTest.hs b/src/Control/Monad/Class/MonadTest.hs --- a/src/Control/Monad/Class/MonadTest.hs +++ b/src/Control/Monad/Class/MonadTest.hs @@ -1,10 +1,10 @@ module Control.Monad.Class.MonadTest (MonadTest (..)) where -import Control.Monad.Reader +import Control.Monad.Reader -- | A helper monad for /IOSimPOR/. class Monad m => MonadTest m where - -- | mark a thread for schedule exploration. All threads that are forked by + -- | Mark a thread for schedule exploration. All threads that are forked by -- it are also included in the exploration. -- exploreRaces :: m () diff --git a/src/Control/Monad/Class/MonadThrow.hs b/src/Control/Monad/Class/MonadThrow.hs --- a/src/Control/Monad/Class/MonadThrow.hs +++ b/src/Control/Monad/Class/MonadThrow.hs @@ -7,6 +7,10 @@ {-# LANGUAGE TupleSections #-} {-# LANGUAGE TypeFamilies #-} +-- | A generalisation of +-- +-- API to both 'IO' and . +-- module Control.Monad.Class.MonadThrow ( MonadThrow (..) , MonadCatch (..) @@ -21,14 +25,14 @@ , catches ) where -import Control.Exception (Exception (..), MaskingState, SomeException) -import qualified Control.Exception as IO -import Control.Monad (liftM) +import Control.Exception (Exception (..), MaskingState, SomeException) +import Control.Exception qualified as IO +import Control.Monad (liftM) -import Control.Monad.Reader (ReaderT (..), runReaderT, lift) +import Control.Monad.Reader (ReaderT (..), lift, runReaderT) -import Control.Monad.STM (STM) -import qualified Control.Monad.STM as STM +import Control.Monad.STM (STM) +import Control.Monad.STM qualified as STM -- | Throwing exceptions, and resource handling in the presence of exceptions. -- diff --git a/src/Control/Monad/Class/MonadTime.hs b/src/Control/Monad/Class/MonadTime.hs --- a/src/Control/Monad/Class/MonadTime.hs +++ b/src/Control/Monad/Class/MonadTime.hs @@ -1,5 +1,9 @@ {-# LANGUAGE DeriveGeneric #-} +-- | and +-- time API compatible with both +-- 'IO' and . +-- module Control.Monad.Class.MonadTime ( MonadTime (..) , MonadMonotonicTimeNSec (..) @@ -10,13 +14,12 @@ , NominalDiffTime ) where -import Control.Monad.Reader +import Control.Monad.Reader -import Data.Time.Clock (NominalDiffTime, UTCTime, - addUTCTime, diffUTCTime) -import qualified Data.Time.Clock as Time -import Data.Word (Word64) -import qualified GHC.Clock as IO (getMonotonicTimeNSec) +import Data.Time.Clock (NominalDiffTime, UTCTime, addUTCTime, diffUTCTime) +import Data.Time.Clock qualified as Time +import Data.Word (Word64) +import GHC.Clock qualified as IO (getMonotonicTimeNSec) class Monad m => MonadMonotonicTimeNSec m where diff --git a/src/Control/Monad/Class/MonadTimer.hs b/src/Control/Monad/Class/MonadTimer.hs --- a/src/Control/Monad/Class/MonadTimer.hs +++ b/src/Control/Monad/Class/MonadTimer.hs @@ -4,20 +4,23 @@ {-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE TypeFamilies #-} --- | Provides classes to handle delays and timeouts. +-- | Provides classes to handle delays and timeouts which generalised +-- API to both 'IO' and +-- . +-- module Control.Monad.Class.MonadTimer ( MonadDelay (..) , MonadTimer (..) ) where -import qualified Control.Concurrent as IO -import Control.Concurrent.Class.MonadSTM -import qualified Control.Concurrent.STM.TVar as STM +import Control.Concurrent qualified as IO +import Control.Concurrent.Class.MonadSTM +import Control.Concurrent.STM.TVar qualified as STM -import Control.Monad.Reader (ReaderT (..)) -import Control.Monad.Trans (lift) +import Control.Monad.Reader (ReaderT (..)) +import Control.Monad.Trans (lift) -import qualified System.Timeout as IO +import System.Timeout qualified as IO -- | A typeclass to delay current thread. class Monad m => MonadDelay m where