Use JuliaFunctional/CompositionsBase.jl?

[tkf]

I created https://github.com/JuliaFunctional/CompositionsBase.jl so that packages dealing with morphisms can share symbols like ⨟, compose, and opcompose (an ASCII alias of ⨟). As we discussed in JuliaFolds/Transducers.jl#67, my motivation is to use this from Transducers.jl. Do you want to use it from Setfield?

I also invited you to the organization so that you can tweak CompositionsBase.jl directly if you need to. Do you want to co-maintain it?

[jw3126]

Thanks for the invite, I am happy to co-maintain it. What do you mean by

Do you want to use it from Setfield?

As I understand, the operations in CompositionBase.jl are all derived from ∘? So they automatically work on lenses without any extra code needed in Setfield.jl?

[tkf]

Ah, I forgot that Setfield.jl didn't export compose.

So, you are right, there is no need for Setfield.jl to import CompositionsBase.jl (unless you want to re-export compose etc.)

[jw3126]

There is one subtle point. Setfield.compose() is a lense, while CompositionBase.compose() throws an error. Its a bit awkward. We could rename Setfield.compose into e.g. lenscompose and reexport CompositionBase if you like.

[tkf]

Setfield.compose() is a lense

Ah, good point. Well, if nobody asked to export this function, I think it's OK to keep it like this. Though probably a super careful approach is to use lenscompose so that it is possible to re-export CompositionsBase.compose from the top-level namespace at some point.