Functor, Applicative, Monad, Foldable, Traversable instances for (, , ) a b

[Edward Kmett]

The Monad instance for pairs came later mostly because there was a big
dependency inversion / orphan problem with getting at Monoid for it, but
yes.

-Edward

On Fri, Mar 31, 2017 at 1:24 PM, Henning Thielemann <
lemming at henning-thielemann.de> wrote:

>
> On Fri, 31 Mar 2017, Herbert Valerio Riedel wrote:
>
> On Thu, Mar 30, 2017 at 10:47 PM Bryan Richter <b at chreekat.net> wrote:
>>       I just don't know why pairs ever got to Functor. I fear this was an
>> ancient decision... no?
>>
>>
>> If you're curious, this happened over 10 years ago:
>>
>> http://git.haskell.org/ghc.git/commitdiff/209bf03ac7949c9bcf
>> 677561a2b1360b158e3b22
>>
>
> Interesting. The Functor instance for pairs was added together with the
> Functor instance for functions. But the Monad instance for pairs came
> later, right?
>
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