[Haskell] Functor ((,) a)

Janis Voigtlaender voigt at tcs.inf.tu-dresden.de
Wed Sep 19 04:24:50 EDT 2007

Dan Doel wrote:
>>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.)
> In GHC 6.6 and above, you'll need to import Control.Monad.Instances (a bit of 
> a weird place to put it, but I guess there's no Control.Functor and such).
> If you have an earlier version than that, I'd say import Control.Monad.Writer 
> at a guess.

Thanks a lot. Works!

BTW, what would have been the easiest way for me to find this out on my 
own? Somehow, I would have hoped to be able to navigate to the 
appropriate point from the mentioned place in the online docs, where it 
is stated that the instance in question exists.

Ciao, Janis.

Dr. Janis Voigtlaender
mailto:voigt at tcs.inf.tu-dresden.de

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