unsafeCoerce.hs

-- courtesy of hpc on #haskell
import Unsafe.Coerce
import Control.Monad.ST

toInteger :: Int -> Integer
isJust    :: Maybe a -> Bool
null      :: [a] -> Bool
id        :: a -> a

toInteger = unsafeCoerce
isJust    = unsafeCoerce
null      = not . unsafeCoerce
id        = unsafeCoerce

newtype Fix f = Fix (f (Fix f))
data Tree a = Leaf a | Branch (Tree a) (Tree a)

treeToLists :: Tree a -> Fix []
treeToLists = unsafeCoerce

unsafeSTToIO :: ST s a -> IO a
unsafeSTToIO = unsafeCoerce

undefined :: a
undefined = unsafeCoerce unsafeCoerce

fixSTM :: (a -> STM a) -> STM a
fixSTM = unsafeCoerce fixIO

isTrue :: Bool -> Bool
isTrue = (unsafeCoerce :: Either a b -> Bool) . (unsafeCoerce :: Maybe c -> Either a b) . (unsafeCoerce :: Bool -> Maybe c)