[commit: parallel] master: cope with chunk sizes smaller than 2 (#5100) (f82611f)

[Simon Marlow]

Repository : ssh://darcs.haskell.org//srv/darcs/packages/parallel

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/f82611fac439236e22a057cd555bb9fe393597b0

>---------------------------------------------------------------

commit f82611fac439236e22a057cd555bb9fe393597b0
Author: Simon Marlow <marlowsd at gmail.com>
Date:   Wed May 18 16:45:37 2011 +0100

    cope with chunk sizes smaller than 2 (#5100)

>---------------------------------------------------------------

 Control/Parallel/Strategies.hs |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/Control/Parallel/Strategies.hs b/Control/Parallel/Strategies.hs
index 7b0cd6f..b37a3f1 100644
--- a/Control/Parallel/Strategies.hs
+++ b/Control/Parallel/Strategies.hs
@@ -428,9 +428,13 @@ parListNth n strat = evalListNth n (rpar `dot` strat)
 -- It is expected that this function will be replaced by a more
 -- generic clustering infrastructure in the future.
 --
+-- If the chunk size is 1 or less, 'parListChunk' is equivalent to
+-- 'parList'
+--
 parListChunk :: Int -> Strategy a -> Strategy [a]
-parListChunk n strat xs =
-  concat `fmap` parList (evalList strat) (chunk n xs)
+parListChunk n strat xs
+  | n <= 1    = parList strat xs
+  | otherwise = concat `fmap` parList (evalList strat) (chunk n xs)
 
 chunk :: Int -> [a] -> [[a]]
 chunk _ [] = []