import "JavaBuiltin" as Java class Num a where (+) :: a -> a -> a (-) :: a -> a -> a instance Num Integer where (+) = Java.iadd (-) = Java.isub (<=) = Java.icmple fibonacci x = if x <= (1 :: Integer) then 1 :: Integer else fibonacci (x - (1 :: Integer)) + fibonacci (x - (2 :: Integer)) main = fibonacci 10 -- 89