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philipnilsson/gist:7b0974e4a8094c04efb3

Created November 19, 2014 01:29
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gistfile1.hs
data Pair a = Pair a a
data Exp typ where
Vec :: Exp a -> Exp a -> Exp (Pair a)
Const :: Int -> Exp Int
-- with type
type RHS typ = String
data Statement typ =
RHS typ := Exp typ
vec :: RHS (Pair Int)
vec = "test"
x = vec := Const 3
-- with data
data RHS' typ = RHS String
data Statement' typ =
RHS' typ ::= Exp typ
vec' :: RHS' (Pair Int)
vec' = RHS "test"
-- will produce expected compile error:
-- Couldn't match type `Int' with `Pair Int'
-- x' = vec' ::= Const 3
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