[Haskell-cafe] Numeric literals

[Lauri Oksanen]

Hi,

Is there some way to tell ghc, how to interpret  numeric literals? I
would like it to interpret
1 as 1 :: Integer
not
1 as fromInteger (1 :: Integer)

I have been playing with the following (rather ugly) code.

{-# OPTIONS
 -XFunctionalDependencies
 -XMultiParamTypeClasses
 -XTypeSynonymInstances
#-}
module Test where
import Prelude(Integer, Double)
import qualified Prelude as P
default(Integer, Double)

type Z = Integer
type R = Double

class Plus a b c | a b -> c where
    (+) :: a -> b -> c

instance Plus Z Z Z where
    j + k =  j P.+ k
instance Plus R R R where
    x + y = x P.+ y

instance Plus R Z R where
    x + j = x P.+ P.fromInteger j
instance Plus Z R R where
    j + x = P.fromInteger j P.+ x

x = (1 :: Z) + (1.0 :: R)
--y = 1 + 1.0

The commented line can't be compiled (because of ambiguous types, I think).

- Lauri