[Haskell] Functor ((,) a)

[Janis Voigtlaender]

Hi,

the Prelude docs found via

http://haskell.org/hoogle/hoodoc.cgi?module=Prelude&name=Functor&mode=class

claim that there is an instance

Functor ((,) a)

And yet, I get (in GHC, but similarly in Hugs):

Prelude> fmap (+1) (undefined,2)

<interactive>:1:0:
     No instance for (Functor ((,) a))
       arising from use of `fmap' at <interactive>:1:0-22
     Possible fix: add an instance declaration for (Functor ((,) a))
     In the expression: fmap ((+ 1)) (undefined, 2)
     In the definition of `it': it = fmap ((+ 1)) (undefined, 2)

What do I have to import to get the Functor ((,) a) instance?

(Of course, I can define it myself, but this is not the point.)

Thanks,
Janis.

-- 
Dr. Janis Voigtlaender
http://wwwtcs.inf.tu-dresden.de/~voigt/
mailto:voigt at tcs.inf.tu-dresden.de