Doing IO in foldr repeats lines?

Hi all The following code:

module Main (main) where

import IO

main :: IO() main = do _ <- foldl foo (return 14) ["qq\n", "ww\n", "ee\n"] putStr ""

foo :: IO Int -> String -> IO Int foo io_l s = do l <- io_l () <- putStr s io_l

prints (with both GHC and hugs): qq ww qq ee qq ww qq and I really don't understand why. Is the code re-evaluated every time foldl is expanded or something? Thanks Ian, confused