monad-fork (empty) → 0.1

raw patch · 5 files changed

+83/−0 lines, 5 filesdep +basedep +monad-controlsetup-changed

Dependencies added: base, monad-control

Files

• CONTRIBUTORS +1/−0
• LICENSE +2/−0
• Setup.hs +2/−0
• monad-fork.cabal +29/−0
• src/Control/Monad/Fork/Class.hs +49/−0

@@ -0,0 +1,1 @@+Robin Banks <anarchomorphism@seomraspraoi.org>

@@ -0,0 +1,2 @@+may the last IP lawyer be hung+with the guts of the last cop

@@ -0,0 +1,2 @@+import Distribution.Simple+main = defaultMain

@@ -0,0 +1,29 @@+name:           monad-fork+version:        0.1+synopsis:       Type class for monads which support a fork operation.+license:        PublicDomain+license-file:   LICENSE+author:         Robin Banks+maintainer:     anarchomorphism@seomraspraoi.org+stability:      Experimental+category:       Control+cabal-version:  >= 1.6+build-type:     Simple++extra-source-files:+  CONTRIBUTORS++Library+  hs-source-dirs:+    src++  exposed-modules:+    Control.Monad.Fork.Class++  build-depends:+    base > 4 && < 5,+    monad-control > 0.3 && < 0.4++source-repository head+  type:     git+  location: git://git.seomraspraoi.org/monad-fork.git

@@ -0,0 +1,49 @@+{-# LANGUAGE FlexibleContexts #-}+{-# LANGUAGE FlexibleInstances #-}+{-# LANGUAGE OverlappingInstances #-}+{-# LANGUAGE UndecidableInstances #-}++module Control.Monad.Fork.Class+    ( MonadFork (..)+    )+where++import           Control.Concurrent (ThreadId, forkIO)+import           Control.Monad (liftM)+import           Control.Monad.Trans.Control+                     ( MonadBaseControl+                     , MonadTransControl+                     , liftBaseDiscard+                     , liftWith+                     )++------------------------------------------------------------------------------+-- | The 'MonadFork' type class, for monads which support a fork operation.+--+-- The instance for 'IO' is simply 'forkIO', while several very overlapping+-- instances are provided for composite monads, using the monad-control+-- package.+--+-- An example of a monad which has a 'MonadFork' instance that is not simply+-- a lifted form of 'forkIO' is the @ResourceT@ monad from the conduit+-- package, which defines the operation @resourceForkIO@. The instances+-- defined here, using the OverlappingInstances extension, will correctly+-- handle the case of monads transformed on top of @ResourceT@ (assuming a+-- definition exists for @ResourceT@).+class MonadFork m where+    fork :: m () -> m ThreadId+++------------------------------------------------------------------------------+instance MonadFork IO where+    fork = forkIO+++------------------------------------------------------------------------------+instance (MonadFork b, MonadBaseControl b m) => MonadFork m where+    fork = liftBaseDiscard fork+++------------------------------------------------------------------------------+instance (MonadTransControl t, MonadFork m, Monad m) => MonadFork (t m) where+    fork m = liftWith $ \run -> fork $ liftM (const ()) $ run m