id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
1752	CSE can create space leaks by increasing sharing	guest		"The following program exhibits a space leak on GHC6.6.1.  ""noleak"" doesn't exhibit the leak.  The only difference is choosing to use $ (leaky) instead of () (non-leaky).

No leak happens if optimizations are off.

Compiled with {{{c:\haskell> ghc -O2 --make fibsquares.hs}}}

{{{
module Main where

fibs a b = a : fibs b (a+b)

odds (x:xs) = evens xs
evens (x:xs) = x : odds xs

square x = x*x
sumSucc xs = zipWith (+) xs (tail xs)

main = spaceleak

spaceleak = 
    mapM_ print $ zip [0..] $ takeWhile id $
    zipWith (==) (odds $ fibs 0 1) $ 
    sumSucc $ map square $ fibs 0 1

noleak =
    mapM_ print $ zip [0..] $ takeWhile id $
    zipWith (==) (odds $ fibs 0 1)
    (sumSucc $ map square $ fibs 0 1)
}}}
"	bug	closed	low	_|_	Compiler	6.6.1	wontfix			Windows	Unknown/Multiple	Runtime performance bug	Unknown