Mikael Johansson writes:

module Main (main) where main = putStrLn "Hello World" end

with the command

ghc Hello.lhs

I get the message on standard output:

No definitions in file <perhaps you forgot the '>'s?>

.lhs means "literate Haskell file". Try

module Main (main) where main = putStrLn "Hello World"

(the "end" isn't legal Haskell). The ">" at the beginning of the line are called "Bird tracks" (after Richard Bird), and mark the lines of a literate Haskell program that are actually code. Lines without them are just comments. Or try \begin{code} module Main (main) where main = putStrLn "Hello World" \end{code} which is another way of marking code. The final way, probably the easiest, is simply to put your program in a file called Hello.hs rather than Hello.lhs. The .hs extension means "ordinary Haskell code". HTH. --KW 8-) -- Keith Wansbrough <kw217@cl.cam.ac.uk> http://www.cl.cam.ac.uk/users/kw217/ Cambridge University Computer Laboratory.