[Haskell-beginners] Parse error: naked expression at top level

Hello, I made this little script : replicate :: Int -> a -> [a] replicate a xs = [xs | x' <= a <--xs] replicate 3 True But when I let it run in GHCi, version 7.0.3 on a FreeBSD box I see this error : oefening.hs:4:1: Parse error: naked expression at top level Failed, modules loaded: none. How can I solve this and what does it mean. Roelof