I don't think that's valid Haskell. Examples of Haskell:

    case (x>y) of {True -> "Yup"; False -> "Nope");}

or

    if (x>y) then "Yup" else "Nope"

An example that uses otherwise would be

    fizzbuzz x | x `mod` 15 == 0 = "Fizzbuzz"
               | x `mod` 5  == 0 = "Buzz"
               | x `mod` 3  == 0 = "Fizz"
               | otherwise       = show x  -- This is x.to_string