monad-coroutine (empty) → 0.5
raw patch · 7 files changed
+1214/−0 lines, 7 filesdep +basedep +monad-paralleldep +transformerssetup-changed
Dependencies added: base, monad-parallel, transformers
Files
- Control/Monad/Coroutine.hs +214/−0
- Control/Monad/Coroutine/Nested.hs +111/−0
- Control/Monad/Coroutine/SuspensionFunctors.hs +62/−0
- LICENSE.txt +674/−0
- Setup.lhs +4/−0
- TestCoroutine.hs +122/−0
- monad-coroutine.cabal +27/−0
+ Control/Monad/Coroutine.hs view
@@ -0,0 +1,214 @@+{- + Copyright 2009-2010 Mario Blazevic++ This file is part of the Streaming Component Combinators (SCC) project.++ The SCC project is free software: you can redistribute it and/or modify it under the terms of the GNU General Public+ License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later+ version.++ SCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty+ of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.++ You should have received a copy of the GNU General Public License along with SCC. If not, see+ <http://www.gnu.org/licenses/>.+-}++-- | This module defines the 'Coroutine' monad transformer.+-- +-- A 'Coroutine' monadic computation can 'suspend' its execution at any time, returning control to its invoker. The+-- returned coroutine suspension is a 'Functor' containing the resumption of the coroutine. Here is an example of a+-- coroutine in the 'IO' monad that suspends computation using the functor 'Yield' from the+-- "Control.Monad.Coroutine.SuspensionFunctors" module:+-- +-- @+-- producer :: Coroutine (Yield Int) IO String+-- producer = do yield 1+-- lift (putStrLn \"Produced one, next is four.\")+-- yield 4+-- return \"Finished\"+-- @+-- +-- To continue the execution of a suspended 'Coroutine', apply its 'resume' method. The easiest way to run a coroutine+-- to completion is by using the 'pogoStick' function, which keeps resuming the coroutine in trampolined style until it+-- completes. Here is an example of 'pogoStick' applied to the /producer/ example above:+-- +-- @+-- printProduce :: Show x => Coroutine (Yield x) IO r -> IO r+-- printProduce producer = pogoStick (\\(Yield x cont) -> lift (print x) >> cont) producer+-- @+-- +-- Multiple concurrent coroutines can be run as well, and this module provides two different ways. The function 'seesaw'+-- can be used to run two interleaved computations. Another possible way is to use the functions 'couple' or 'merge' to+-- weave together steps of different coroutines into a single coroutine, which can then be executed by 'pogoStick'.+-- +-- For other uses of trampoline-style coroutines, see+-- +-- > Trampolined Style - Ganz, S. E. Friedman, D. P. Wand, M, ACM SIGPLAN NOTICES, 1999, VOL 34; NUMBER 9, pages 18-27+-- +-- and+-- +-- > The Essence of Multitasking - William L. Harrison, Proceedings of the 11th International Conference on Algebraic+-- > Methodology and Software Technology, volume 4019 of Lecture Notes in Computer Science, 2006++{-# LANGUAGE ScopedTypeVariables, Rank2Types, EmptyDataDecls #-}++module Control.Monad.Coroutine+ (+ -- * Coroutine definition+ Coroutine(Coroutine),+ resume, suspend,+ -- * Coroutine operations+ mapMonad, mapSuspension, + -- * Running Coroutine computations+ Naught, runCoroutine, pogoStick, foldRun, seesaw, SeesawResolver(..),+ -- * Nested and coupled Coroutine computations+ NestedFunctor (NestedFunctor), SomeFunctor(..), nest,+ couple, merge+ )+where++import Control.Monad (liftM, when)+import Control.Monad.Trans (MonadTrans(..), MonadIO(..))+import Data.Either (either, partitionEithers)+import Data.Traversable (Traversable, sequence)++import Control.Monad.Parallel++-- | Suspending, resumable monadic computations.+newtype Coroutine s m r = Coroutine {+ -- | Run the next step of a `Coroutine` computation. The result of the step execution will be either a suspension or+ -- the final coroutine result.+ resume :: m (Either (s (Coroutine s m r)) r)+ }++type CoroutineStepResult s m r = Either (s (Coroutine s m r)) r++instance (Functor s, Monad m) => Monad (Coroutine s m) where+ return x = Coroutine (return (Right x))+ t >>= f = Coroutine (resume t >>= apply f)+ where apply f (Right x) = resume (f x)+ apply f (Left s) = return (Left (fmap (>>= f) s))+-- t >>= f = Coroutine (resume t >>= either (return . Left . fmap (>>= f)) (resume . f))++instance (Functor s, MonadParallel m) => MonadParallel (Coroutine s m) where+ bindM2 f t1 t2 = Coroutine (bindM2 combine (resume t1) (resume t2)) where+ combine (Right x) (Right y) = resume (f x y)+ combine (Left s) (Right y) = return $ Left (fmap (flip f y =<<) s)+ combine (Right x) (Left s) = return $ Left (fmap (f x =<<) s)+ combine (Left s1) (Left s2) = return $ Left (fmap (bindM2 f $ suspend s1) s2)++instance Functor s => MonadTrans (Coroutine s) where+ lift = Coroutine . liftM Right++instance (Functor s, MonadIO m) => MonadIO (Coroutine s m) where+ liftIO = lift . liftIO++-- | The 'Naught' functor instance doesn't contain anything and cannot be constructed. Used for building non-suspendable+-- coroutines.+data Naught x+instance Functor Naught where+ fmap f _ = undefined++-- | Combines two functors into one, applying both.+newtype NestedFunctor l r x = NestedFunctor (l (r x))+instance (Functor l, Functor r) => Functor (NestedFunctor l r) where+ fmap f (NestedFunctor lr) = NestedFunctor ((fmap . fmap) f lr)++-- | Combines two functors into one, applying either or both of them. Used for coupled coroutines.+data SomeFunctor l r x = LeftSome (l x) | RightSome (r x) | Both (NestedFunctor l r x)+instance (Functor l, Functor r) => Functor (SomeFunctor l r) where+ fmap f (LeftSome l) = LeftSome (fmap f l)+ fmap f (RightSome r) = RightSome (fmap f r)+ fmap f (Both lr) = Both (fmap f lr)++-- | Combines two values under two functors into a pair of values under a single 'NestedFunctor'.+nest :: (Functor a, Functor b) => a x -> b y -> NestedFunctor a b (x, y)+nest a b = NestedFunctor $ fmap (\x-> fmap ((,) x) b) a++-- | Suspend the current 'Coroutine'.+suspend :: (Monad m, Functor s) => s (Coroutine s m x) -> Coroutine s m x+suspend s = Coroutine (return (Left s))++-- | Change the base monad of a 'Coroutine'.+mapMonad :: forall s m m' x. (Functor s, Monad m, Monad m') =>+ (forall x. m x -> m' x) -> Coroutine s m x -> Coroutine s m' x+mapMonad f cort = Coroutine {resume= liftM map' (f $ resume cort)}+ where map' (Right r) = Right r+ map' (Left s) = Left (fmap (mapMonad f) s)++-- | Change the suspension functor of a 'Coroutine'.+mapSuspension :: forall s s' m x. (Functor s, Monad m) => (forall x. s x -> s' x) -> Coroutine s m x -> Coroutine s' m x+mapSuspension f cort = Coroutine {resume= liftM map' (resume cort)}+ where map' (Right r) = Right r+ map' (Left s) = Left (f $ fmap (mapSuspension f) s)++-- | Convert a non-suspending 'Coroutine' to the base monad.+runCoroutine :: Monad m => Coroutine Naught m x -> m x+runCoroutine = pogoStick (error "runCoroutine can run only a non-suspending coroutine!")++-- | Run a suspendable 'Coroutine', using a function that extracts the coroutine resumption from each suspension.+pogoStick :: Monad m => (s (Coroutine s m x) -> Coroutine s m x) -> Coroutine s m x -> m x+pogoStick reveal t = resume t+ >>= \s-> case s + of Right result -> return result+ Left c -> pogoStick reveal (reveal c)++-- | Runs a suspendable coroutine much like 'pogoStick', but allows the resumption function to thread an arbitrary+-- state as well.+foldRun :: Monad m => (a -> s (Coroutine s m x) -> (a, Coroutine s m x)) -> a -> Coroutine s m x -> m (a, x)+foldRun f a t = resume t+ >>= \s-> case s + of Right result -> return (a, result)+ Left c -> uncurry (foldRun f) (f a c)++-- | Weaves two coroutines into one. The two coroutines suspend and resume in lockstep.+couple :: forall s1 s2 m x y r. (Monad m, Functor s1, Functor s2) => + (forall x y r. (x -> y -> m r) -> m x -> m y -> m r)+ -> Coroutine s1 m x -> Coroutine s2 m y -> Coroutine (SomeFunctor s1 s2) m (x, y)+couple runPair t1 t2 = Coroutine{resume= runPair proceed (resume t1) (resume t2)} where+ proceed :: CoroutineStepResult s1 m x -> CoroutineStepResult s2 m y -> m (CoroutineStepResult (SomeFunctor s1 s2) m (x, y))+ proceed (Right x) (Right y) = return $ Right (x, y)+ proceed (Left s1) (Left s2) = return $ Left $ fmap (uncurry (couple runPair)) (Both $ nest s1 s2)+ proceed (Right x) (Left s2) = return $ Left $ fmap (couple runPair (return x)) (RightSome s2)+ proceed (Left s1) (Right y) = return $ Left $ fmap (flip (couple runPair) (return y)) (LeftSome s1)++-- | Weaves a list of coroutines with the same suspension functor type into a single coroutine. The coroutines suspend+-- and resume in lockstep.+merge :: forall s m x. (Monad m, Functor s) =>+ (forall x. [m x] -> m [x]) -> (forall x. [s x] -> s [x])+ -> [Coroutine s m x] -> Coroutine s m [x]+merge sequence1 sequence2 corts = Coroutine{resume= liftM step $ sequence1 (map resume corts)} where+ step :: [CoroutineStepResult s m x] -> CoroutineStepResult s m [x]+ step list = case partitionEithers list+ of ([], ends) -> Right ends+ (suspensions, ends) -> Left $ fmap (merge sequence1 sequence2 . (map return ends ++)) $+ sequence2 suspensions++-- | A simple record containing the resolver functions for all possible coroutine pair suspensions.+data SeesawResolver s1 s2 = SeesawResolver {+ resumeLeft :: forall t. s1 t -> t, -- ^ resolves the left suspension functor into the resumption it contains+ resumeRight :: forall t. s2 t -> t, -- ^ resolves the right suspension into its resumption+ resumeAny :: forall t1 t2 r.+ (t1 -> r) -- ^ continuation to resume only the left suspended coroutine+ -> (t2 -> r) -- ^ continuation to resume the right coroutine only+ -> (t1 -> t2 -> r) -- ^ continuation to resume both coroutines+ -> s1 t1 -- ^ left suspension+ -> s2 t2 -- ^ right suspension+ -> r+ -- ^ invoked when both coroutines are suspended, resolves both suspensions or either one+}++-- | Runs two coroutines concurrently. The first argument is used to run the next step of each coroutine, the next to+-- convert the left, right, or both suspensions into the corresponding resumptions.+seesaw :: (Monad m, Functor s1, Functor s2) => + (forall x y r. (x -> y -> m r) -> m x -> m y -> m r)+ -> SeesawResolver s1 s2+ -> Coroutine s1 m x -> Coroutine s2 m y -> m (x, y)+seesaw runPair resolver t1 t2 = seesaw' t1 t2 where+ seesaw' t1 t2 = runPair proceed (resume t1) (resume t2)+ proceed (Right x) (Right y) = return (x, y)+ proceed (Right x) (Left s2) = seesaw' (return x) (resumeRight resolver s2)+ proceed (Left s1) (Right y) = seesaw' (resumeLeft resolver s1) (return y)+ proceed (Left s1) (Left s2) =+ resumeAny resolver (flip seesaw' (suspend s2)) (seesaw' (suspend s1)) seesaw' s1 s2
+ Control/Monad/Coroutine/Nested.hs view
@@ -0,0 +1,111 @@+{- + Copyright 2010 Mario Blazevic++ This file is part of the Streaming Component Combinators (SCC) project.++ The SCC project is free software: you can redistribute it and/or modify it under the terms of the GNU General Public+ License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later+ version.++ SCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty+ of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.++ You should have received a copy of the GNU General Public License along with SCC. If not, see+ <http://www.gnu.org/licenses/>.+-}++-- | This module defines nestable suspension functors for use with the 'Coroutine' monad transformer, as well as+-- functions for running nested coroutines of this sort.+-- +-- Coroutines can be run from within another coroutine. In this case, the nested coroutines always suspend to their+-- invoker. If a function from this module, such as 'pogoStickNested', is used to run a nested coroutine, the parent+-- coroutine can be automatically suspended as well. A single suspension can thus suspend an entire chain of nested+-- coroutines.+-- +-- Nestable coroutines of this kind should group their suspension functors into an 'EitherFunctor'. You can adjust a+-- normal suspension, such as the one produced by 'yield', using functions 'mapSuspension' and 'liftOut'. To run nested+-- coroutines, use functions 'pogoStickNested', 'seesawNested', and 'coupleNested'.++{-# LANGUAGE ScopedTypeVariables, Rank2Types, MultiParamTypeClasses, TypeFamilies,+ FlexibleContexts, FlexibleInstances, OverlappingInstances, UndecidableInstances+ #-}++module Control.Monad.Coroutine.Nested+ (+ pogoStickNested, coupleNested, seesawNested, + AncestorFunctor,+ liftOut+ )+where++import Control.Monad (join, liftM)+import Control.Monad.Trans (lift)++import Control.Monad.Coroutine+import Control.Monad.Coroutine.SuspensionFunctors++-- | Run a nested 'Coroutine' that can suspend both itself and the current 'Coroutine'.+pogoStickNested :: forall s1 s2 m x. (Functor s1, Functor s2, Monad m) => + (s2 (Coroutine (EitherFunctor s1 s2) m x) -> Coroutine (EitherFunctor s1 s2) m x)+ -> Coroutine (EitherFunctor s1 s2) m x -> Coroutine s1 m x+pogoStickNested reveal t = + Coroutine{resume= resume t+ >>= \s-> case s+ of Right result -> return (Right result)+ Left (LeftF s) -> return (Left (fmap (pogoStickNested reveal) s))+ Left (RightF c) -> resume (pogoStickNested reveal (reveal c))}++-- | Weaves two nested coroutines into one.+coupleNested :: forall s0 s1 s2 m x y r. (Monad m, Functor s0, Monad s0, Functor s1, Functor s2) => + (forall x y r. (x -> y -> m r) -> m x -> m y -> m r)+ -> Coroutine (EitherFunctor s0 s1) m x -> Coroutine (EitherFunctor s0 s2) m y+ -> Coroutine (EitherFunctor s0 (SomeFunctor s1 s2)) m (x, y)+coupleNested runPair = coupleNested' where+ coupleNested' t1 t2 = Coroutine{resume= runPair (\ st1 st2 -> return (proceed st1 st2)) (resume t1) (resume t2)}+ proceed (Right x) (Right y) = Right (x, y)+ proceed (Left (RightF s)) (Right y) = Left $ RightF $ fmap (flip coupleNested' (return y)) (LeftSome s)+ proceed (Right x) (Left (RightF s)) = Left $ RightF $ fmap (coupleNested' (return x)) (RightSome s)+ proceed (Left (RightF s1)) (Left (RightF s2)) =+ Left $ RightF $ fmap (uncurry coupleNested') (Both $ nest s1 s2)+ proceed l (Left (LeftF s)) = Left $ LeftF $ fmap (coupleNested' (Coroutine $ return l)) s+ proceed (Left (LeftF s)) r = Left $ LeftF $ fmap (flip coupleNested' (Coroutine $ return r)) s++-- | Like 'seesaw', but for nested coroutines that are allowed to suspend the current coroutine as well as themselves.+-- If both coroutines try to suspend the current coroutine in the same step, the left coroutine's suspension will have+-- precedence.+seesawNested :: (Monad m, Functor s0, Functor s1, Functor s2) =>+ (forall x y r. (x -> y -> m r) -> m x -> m y -> m r)+ -> SeesawResolver s1 s2+ -> Coroutine (EitherFunctor s0 s1) m x -> Coroutine (EitherFunctor s0 s2) m y -> Coroutine s0 m (x, y)+seesawNested runPair resolver t1 t2 = seesaw' t1 t2 where+ seesaw' t1 t2 = Coroutine{resume= bouncePair t1 t2}+ bouncePair t1 t2 = runPair proceed (resume t1) (resume t2)+ proceed (Left (LeftF s1)) state2 = return $ Left $ fmap ((flip seesaw' (Coroutine $ return state2))) s1+ proceed state1 (Left (LeftF s2)) = return $ Left $ fmap (seesaw' (Coroutine $ return state1)) s2+ proceed (Right x) (Right y) = return $ Right (x, y)+ proceed state1@(Right x) (Left (RightF s2)) = proceed state1 =<< resume (resumeRight resolver s2)+ proceed (Left (RightF s1)) state2@(Right y) = flip proceed state2 =<< resume (resumeLeft resolver s1)+ proceed state1@(Left (RightF s1)) state2@(Left (RightF s2)) =+ resumeAny resolver ((flip proceed state2 =<<) . resume) ((proceed state1 =<<) . resume) bouncePair s1 s2++-- | Class of functors that can contain another functor.+class Functor c => ChildFunctor c where+ type Parent c :: * -> *+ wrap :: Parent c x -> c x+instance (Functor p, Functor s) => ChildFunctor (EitherFunctor p s) where+ type Parent (EitherFunctor p s) = p+ wrap = LeftF++-- | Class of functors that can be lifted.+class (Functor a, Functor d) => AncestorFunctor a d where+ -- | Convert the ancestor functor into its descendant. The descendant functor typically contains the ancestor.+ liftFunctor :: a x -> d x++instance Functor a => AncestorFunctor a a where+ liftFunctor = id+instance (Functor a, ChildFunctor d, d' ~ Parent d, AncestorFunctor a d') => AncestorFunctor a d where+ liftFunctor = wrap . (liftFunctor :: a x -> d' x)++-- | Converts a coroutine into a descendant nested coroutine.+liftOut :: forall m a d x. (Monad m, Functor a, AncestorFunctor a d) => Coroutine a m x -> Coroutine d m x+liftOut cort = mapSuspension liftFunctor cort
+ Control/Monad/Coroutine/SuspensionFunctors.hs view
@@ -0,0 +1,62 @@+{- + Copyright 2010 Mario Blazevic++ This file is part of the Streaming Component Combinators (SCC) project.++ The SCC project is free software: you can redistribute it and/or modify it under the terms of the GNU General Public+ License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later+ version.++ SCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty+ of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.++ You should have received a copy of the GNU General Public License along with SCC. If not, see+ <http://www.gnu.org/licenses/>.+-}++-- | This module defines suspension functors for use with the "Control.Monad.Coroutine" module.+-- ++module Control.Monad.Coroutine.SuspensionFunctors+ (+ -- * Suspension functors+ Yield(Yield), Await(Await), Request(Request), EitherFunctor(LeftF, RightF),+ yield, await, request+ )+where++import Control.Monad (Monad)+import Control.Monad.Coroutine (Coroutine, resume, suspend)++-- | The 'Yield' functor instance is equivalent to (,) but more descriptive.+data Yield x y = Yield x y+instance Functor (Yield x) where+ fmap f (Yield x y) = Yield x (f y)++-- | The 'Await' functor instance is equivalent to (->) but more descriptive.+newtype Await x y = Await (x -> y)+instance Functor (Await x) where+ fmap f (Await g) = Await (f . g)++-- | The 'Request' functor instance combines a 'Yield' of a request with an 'Await' for a response.+data Request request response x = Request request (response -> x)+instance Functor (Request x f) where+ fmap f (Request x g) = Request x (f . g)++-- | Combines two alternative functors into one, applying one or the other. Used for nested coroutines.+data EitherFunctor l r x = LeftF (l x) | RightF (r x)+instance (Functor l, Functor r) => Functor (EitherFunctor l r) where+ fmap f (LeftF l) = LeftF (fmap f l)+ fmap f (RightF r) = RightF (fmap f r)++-- | Suspend yielding a value.+yield :: Monad m => x -> Coroutine (Yield x) m ()+yield x = suspend (Yield x (return ()))++-- | Suspend until a value is provided.+await :: Monad m => Coroutine (Await x) m x+await = suspend (Await return)++-- | Suspend yielding a request and awaiting the response.+request :: Monad m => x -> Coroutine (Request x y) m y+request x = suspend (Request x return)
+ LICENSE.txt view
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+ Setup.lhs view
@@ -0,0 +1,4 @@+#! /usr/bin/env runhaskell+ +> import Distribution.Simple+> main = defaultMain
+ TestCoroutine.hs view
@@ -0,0 +1,122 @@+{- + Copyright 2010 Mario Blazevic++ This file is part of the Streaming Component Combinators (SCC) project.++ The SCC project is free software: you can redistribute it and/or modify it under the terms of the GNU General Public+ License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later+ version.++ SCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty+ of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.++ You should have received a copy of the GNU General Public License along with SCC. If not, see+ <http://www.gnu.org/licenses/>.+-}++-- | The "Control.Monad.Coroutine" tests.++module Main where++import Prelude hiding (sequence)+import Control.Exception (assert)+import Control.Monad (liftM, mapM, when)+import Control.Monad.Identity (runIdentity)+import Control.Parallel (pseq)+import Data.List (find)+import Data.Maybe (fromJust)+import System.Environment (getArgs)++import Control.Monad.Coroutine+import Control.Monad.Coroutine.SuspensionFunctors+import Control.Monad.Coroutine.Nested+import Control.Monad.Parallel (MonadParallel(..), sequence)++factors n = maybe [n] (\k-> (k : factors (n `div` k))) (find (\k-> n `mod` k == 0) [2 .. n - 1])++fib x 0 | x >= 0 = 1+fib _ 1 = 1+fib x n = fib x (n - 2) + fib x (n - 1)++factorFibs :: MonadParallel m => [Int] -> m Integer+factorFibs nums = liftM snd $+ seesaw bindM2 (SeesawResolver resumeLeft resumeRight resumeAny)+ (mapM_ (yieldApply (fib 0)) nums)+ (factorize 0)+ where factorize :: MonadParallel m => Integer -> Coroutine (Await (Maybe Integer)) m Integer+ factorize sum = await+ >>= maybe+ (return sum)+ (\n-> factorize (sum + n {-product (factors n)-}))+ resumeLeft (Yield _ c) = c+ resumeRight (Await c) = c Nothing+ resumeAny _ _ c (Yield x c1) (Await c2) = c c1 (c2 (Just x))++twoFibs :: MonadParallel m => [Int] -> m Integer+twoFibs nums = liftM (uncurry (+)) $+ pogoStick+ resume+ (couple bindM2 (fibs 1) (fibs 2))+ where resume :: SomeFunctor (Yield Integer) (Yield Integer) c -> c+ resume (Both (NestedFunctor (Yield n1 (Yield n2 c)))) = assert (n1 == n2) c+ fibs ix = mapM_ (yieldApply (fib ix)) nums >> return (fib ix $ last nums)++twoFibsSeesaw :: MonadParallel m => [Int] -> m Integer+twoFibsSeesaw nums = liftM (uncurry (+)) $+ seesaw bindM2 resolver (fibs 1) (fibs 2)+ where resolver = SeesawResolver{+ resumeLeft= undefined,+ resumeRight= undefined,+ resumeAny= \resumeLeft resumeRight resumeBoth (Yield left c1) (Yield right c2)->+ assert (left == right) $ resumeBoth c1 c2+ }+ fibs ix = mapM_ (yieldApply (fib ix)) nums >> return (fib ix $ last nums)++fibs :: MonadParallel m => Int -> [Int] -> m Integer+fibs coroutineCount nums = liftM sum $+ pogoStick+ resume+ (merge sequence appendYields $ replicateIx coroutineCount fibs)+ where resume :: Yield [Integer] (Coroutine (Yield [Integer]) m [Integer]) -> Coroutine (Yield [Integer]) m [Integer]+ resume (Yield (x:xs) c) = assert (all (==x) xs) c+ fibs ix = mapM_ (yieldApply ((:[]) . fib ix)) nums >> return (fib ix $ last nums)+ appendYields :: [Yield [s] x] -> Yield [s] [x]+ appendYields yields = uncurry Yield $ foldr (\(Yield s x) (ss, xs)-> (s ++ ss, x:xs)) ([], []) yields++yieldApply f n = let result = f n in result `pseq` yield result++replicateIx :: Int -> (Int -> x) -> [x]+replicateIx n f = map f [1..n]++nested :: (Monad m, Functor p) =>+ Int -> (Integer -> Coroutine p m ()) -> Coroutine (EitherFunctor p (Yield Integer)) m ()+nested level suspendParent = do mapSuspension RightF (yield 1)+ liftOut (suspendParent 2)+ when (level > 0) (pogoStickNested cont $ nested (pred level) (liftOut . suspendParent))+ where cont (Yield x c) = c++main = do args <- getArgs+ if length args /= 4+ then putStr help+ else do let [taskName, monad, size, coroutineCount] = args+ task :: MonadParallel m => m Integer+ task = case taskName of "fib-factor" -> factorFibs [1 .. read size]+ "2fibs" -> twoFibs [1 .. read size]+ "2fibsSeesaw" -> twoFibsSeesaw [1 .. read size]+ "fibs" -> fibs (read coroutineCount) [1 .. read size]+ "nested" -> liftM fst $ foldRun add 0 (nested (read size) yield)+ where add s (LeftF (Yield n c)) = (s + n, c)+ add s (RightF (Yield n c)) = (s + 10 * n, c)+ _ -> error (help ++ "Bad task.")+ result <- case monad of "Maybe" -> return $ fromJust task+ "[]" -> return $ head task+ "Identity" -> return $ runIdentity task+ "IO" -> task+ _ -> error (help ++ "Bad monad.")+ print result++help = "Usage: test-coroutine <task> <monad> <size> <coroutines>?\n"+ ++ " where <task> is 'fib-factor' or 'fibs',\n"+ ++ " <monad> is 'Identity', 'Maybe', '[]', or 'IO',\n"+ ++ " <size> is the size of the task,\n"+ ++ " and <coroutines> is the number of coroutines to employ.\n"
+ monad-coroutine.cabal view
@@ -0,0 +1,27 @@+Name: monad-coroutine+Version: 0.5+Cabal-Version: >= 1.2+Build-Type: Simple+Synopsis: Coroutine monad transformer for suspending and resuming monadic computations+Category: Concurrency, Control, Monads+Tested-with: GHC+Description:+ This package defines a monad transformer, applicable to any monad, that allows the monadic computation to suspend and+ to be later resumed. The transformer is parameterized by an arbitrary functor, used to store the suspended+ computation's resumption.+ +License: GPL+License-file: LICENSE.txt+Copyright: (c) 2010 Mario Blazevic+Author: Mario Blazevic+Maintainer: blamario@yahoo.com+Homepage: http://trac.haskell.org/SCC/wiki/monad-coroutine+Extra-source-files: TestCoroutine.hs+-- Source-repository head+-- type: darcs+-- location: http://code.haskell.org/SCC/++Library+ Exposed-Modules: Control.Monad.Coroutine, Control.Monad.Coroutine.SuspensionFunctors, Control.Monad.Coroutine.Nested+ Build-Depends: base < 5, monad-parallel, transformers+ GHC-prof-options: -auto-all