Add Chipped type

[LiamGoodacre]

"Traversable containers which hold Maybe are witherable."

https://hackage.haskell.org/package/witherable-0.1.3.3/docs/Data-Witherable.html#t:Chipped

[LiamGoodacre]

Functor t => Filterable (Chipped t)
Traversable t => Witherable (Chipped t)

[joneshf]

How does this differ from MaybeT f a?

[LiamGoodacre]

@joneshf absolutely no difference. I'm debating between:

• adding Chipped
• depending on purescript-transformers with appropriate instances
• not doing anything

[joneshf]

Another options is transformers depends on this library.

[JordanMartinez]

Now that this library is one of the core libraries, @joneshf's proposal should be re-examined as a possible way forward.

[LiamGoodacre]

I think an alternative to chipped might be to have an instance for composition, then use (f ∘ Maybe) rather than Chipped f.

(Traversable f, Witherable g) => Witherable (f ∘ g)

I haven't thought about it very much, so may or may not be lawful.