Add missing Monad/Traversable instances to tuples

[Ganesh Sittampalam]

On 03/04/2019 02:27, Carter Schonwald wrote:

> so from my perspective, while yes, some folks use tuples for fixed size
> homogenuous collections, they are useful powerful tools in the algebra
> of types and functional programming jiggery pokery! There is no sound
> reason to cripple our official prepresentative of the the simple
> polymorphic product type formal, the "*" of our haskell and the eternal
> dual of the sum of our cases! ;)
> 
> strong +1, let the algebras roar :) 
> 
> to be clear, the arguments against are valid, but i thnk they could be
> addressed by identifying the changes / tooling that would enable a
> better fitting of intent. buggy code happens, fix the root, not the symptom

For the record I think the root cause here *is* the instances, and
anything we do later is just sticking plaster. In my mind the instances
are the moral equivalent of using dynamic types.

Cheers,

Ganesh