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1 files changed, 16 insertions, 0 deletions

diff --git a/ch10_10.0.example.hs b/ch10_10.0.example.hs
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+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE TypeFamilies #-}
+
+import Data.Kind (Type)
+
+type Exp a = a -> Type
+
+type family Eval (e :: Exp a) :: a
+
+data Fst :: (a, b) -> Exp a
+
+data Snd :: (a, b) -> Exp b
+
+type instance Eval (Fst '(a, b)) = a
+
+type instance Eval (Snd '(a, b)) = b