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 <[EMAIL PROTECTED]>
http://www.cl.cam.ac.uk/users/kw217/
Cambridge University Computer Laboratory.
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