[Haskell] IN Doubt...

[Don Stewart]

hg.manuel:
>    Dear Haskellers,
>    
>             why this program is not accepted by Hugs?
>    
>    equal a a = True
>    equal a b | not(a==b) = False

You can't pattern match 'a' and 'a' like that -- there's no implicit
unification.

Instead, I'd write:

    equal a b
        | a == b    = True
        | otherwise = False

Well actually, maybe I'd write:

    equal a b = a == b

In reality, though:

    equal = (==)

And then I'd just use (==) directly :)

Cheers,
  Don