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

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@henning-thielemann.de> wrote:

On Fri, 31 Mar 2017, Herbert Valerio Riedel wrote:

On Thu, Mar 30, 2017 at 10:47 PM Bryan Richter 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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