Re: Proposal: merge Data.Functor.Coproduct into transformers

On 12/11/12 7:27 AM, Mario Blazevic wrote:

On Tue, Dec 11, 2012 at 5:29 AM, Edward Kmett wrote:

...

I'm not wedded to its current behavior of wrapping an Either. It was kind of nice that converting to and from Either was a no-op on GHC, but that could change.

I agree that I wouldn't want to add functions named 'left' and 'right', so moving to a data type rather than a newtype seems reasonable.

Perhaps

data Coproduct f g a = LeftF (f a) | RightF (g a)

would be a nice color for the bikeshed?

+1. I hesitate to suggest another alternative, but if folks are displeased with those names, there's always the tried and true InL/InR or InjL/InjR. But given the precedent of Either, I think LeftF/RightF have a nice ring to them.

Nah, those constructor names are dumb. I prefer Shaun's

...

data Sum f g a = SumLeft (f a) | SumRight (g a)

-1. What happened to the vaunted brevity? I type out the names of data constructors far more often than the names of type constructors. And those data constructor names are obnoxiously long for something as basic as a functor coproduct. -- Live well, ~wren