GHC/Data Parallel Haskell/GHC.PArr

Convenience without the speed: syntactic sugar for a high-level array library

Any recent stable version of GHC (e.g., version 6.6) includes syntactic support for array comprehensions and a library of frequently used array operations. To use these, you need to pass GHC the command line option -fparr (to enable the extra syntax) and import the module GHC.PArr (a Prelude extension for arrays). (If you like to use parallel array comprehensions, you also need -fglasgow-exts.) For example, the following module implements a dot product using arrays:

{-# OPTIONS -fparr -fglasgow-exts #-}
module DotP (dotp)
where
import GHC.PArr

dotp :: Num a => [:a:] -> [:a:] -> a
dotp xs ys = sumP [:x * y | x <- xs | y <- ys:]

You can use this module in an interactive GHCi session as follows:

Prelude> :set -fparr -fglasgow-exts
Prelude> :load DotP
[1 of 1] Compiling DotP             ( code/haskell/DotP.hs, interpreted )
Ok, modules loaded: DotP.
*DotP> dotp [:1..3:] [:4..6:]
32
*DotP>

(NB: The :set is needed despite the OPTIONS pragma in DotP.hs, so that you can use array syntax on the interactive command line of GHCi.)

Unfortunately, the current version of Haddock does not grok the special array syntax, so there is no nice HTML version of the interface for GHC.PArr. Instead, please consult the source code of GHC.PArr.