formatting and guarded expressions

Hi,

Are there special formatting constraints for using guards in Hugs?

My students are learning Haskell in lab and the following simple function
sometimes fails

>fact n
>     | n == 0 = 1
>     | otherwise = n * (fact(n-1))

Hugs complains about an unexpected ;

Sometimes code after a guarded expression fixes the problem. We've tried
putting the | up against the > or underneath the parameter. The same code
seems to work for some students but not for others.

Any ideas?

- Lea