[Haskell-cafe] Space leak with replicateM

In the following program, the function "test1" results in huge memory usage, but substituting "test2", which does essentially the same thing, does not. GHC 7.10.1, AMD64. Is there a different implementation of replicateM that avoids the space leak? module Main where { import Control.Monad; numbers :: [Int]; numbers=[1..200]; -- has a space leak test1 :: [[Int]]; test1 = replicateM 4 numbers; -- no space leak test2 :: [[Int]]; test2 = do { x1 <- numbers; x2 <- numbers; x3 <- numbers; x4 <- numbers; return [x1,x2,x3,x4]; }; main :: IO(); main = print $ length $ test1; } Thanks, --ken