[Haskell-beginners] turning a value into an expression

[Deniz Dogan]

2009/11/9 John Moore <john.moore54 at gmail.com>:
> Hi,
>    How do I turn a value into an expression
> I want to do for e.g. 8 - 1 turn it into (subtract (Val8) (Val1)
>
> Any ideas
>
> J
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import Prelude hiding ((-))

data Val a = Val a
  deriving Show

data Expr a b = Subtract a b
  deriving Show

(-) :: Num a => a -> a -> Expr (Val a) (Val a)
x - y = Subtract (Val x) (Val y)



> 4 - 3
Subtract (Val 4) (Val 3)

-- 
Deniz Dogan