foobuzz n = f (n `mod` 3 == 0) (n `mod` 5 == 0)
    where
        f True True = "foobuzz"
        f True _ = "foo"
        f _ True = "buzz"
        f _ _ = ""

foobuzz_if n = if n `mod` 15 == 0 then "foobuzz" else if n `mod` 5 == 0 then "buzz" else if n `mod` 3 == 0 then "foo" else ""