Unboxed sums
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{-# LANGUAGE MagicHash #-}
{-# LANGUAGE UnboxedSums #-}
module Main
( main
) where
import GHC.Int (Int (..))
import GHC.Prim (Int#)
type MaybeInt = (# Int# | () #)
maybeInt :: a -> (Int# -> a) -> MaybeInt -> a
maybeInt _ f (# i | #) = f i
maybeInt z _ (# | () #) = z
main :: IO ()
main = do
print $ maybeInt 0 I# (# 1# | #)
print $ maybeInt 0 I# (# | () #)
Haskell
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