----------------------------------------------------------------------------- -- | -- Module : Control.Parallel -- Copyright : (c) The University of Glasgow 2001 -- License : BSD-style (see the file libraries/base/LICENSE) -- -- Maintainer : libraries@haskell.org -- Stability : experimental -- Portability : non-portable -- -- Parallel Constructs -- ----------------------------------------------------------------------------- module Control.Parallel ( par, seq -- re-exported ) where import Prelude -- Maybe parIO and the like could be added here later. -- | Indicates that it may be beneficial to evaluate the first -- argument in parallel with the second. Returns the value of the -- second argument. -- -- @a `par` b@ is exactly equivalent semantically to @b@. -- -- @par@ is generally used when the value of @a@ is likely to be -- required later, but not immediately. Also it is a good idea to -- ensure that @a@ is not a trivial computation, otherwise the cost of -- spawning it in parallel overshadows the benefits obtained by -- running it in parallel. -- -- Note that actual parallelism is only supported by certain -- implementations (GHC with the @-threaded@ option, and GPH, for -- now). On other implementations, @par a b = b@. -- par :: a -> b -> b -- For now, Hugs does not support par properly. par a b = b