Y Combinator in Haskell

YCombinator.hs

import Unsafe.Coerce

y :: (a -> a) -> a
y = \f -> (\x -> f (unsafeCoerce x x))(\x -> f (unsafeCoerce x x))

-- Ref: [Y Combinator in Haskell](http://stackoverflow.com/questions/4273413/y-combinator-in-haskell)
-- a fibonacci example
main = putStrLn $ show $ y (\fact -> \n -> if n < 2 then 1 else n * fact (n - 1)) 5

in scala:
def Y[A, B](f: %28A => B%29 => %28A => B%29): A => B = f(Y(f))(_)