`==` not defined for `IndexLens`

[sunxd3]

We are trying to update Turing.jl to using Accessors.jl in sync with BangBang (TuringLang/AbstractPPL.jl#91)

I noticed that == for IndexLens is not defined, (c.f. Setfield's definition).

Are there reasons this is removed (or just not ported)?

[jw3126]

Thanks a lot for bringing this up. Hash and equality should be defined in the same ways as in Setfield. The only exception are compositions, which use Base.\circ.

[sunxd3]

Just started a PR at #146.

For equality comparisons between ComposedOptic, I kept the original definition. @jw3126 can you clarity why do we need circ (or opcompose) in this case?

[jw3126]

Just started a PR at #146.

For equality comparisons between ComposedOptic, I kept the original definition. @jw3126 can you clarity why do we need circ (or opcompose) in this case?

julia> using Accessors

julia> Accessors.ComposedOptic
ComposedFunction

So ComposedOptic is just an alias and owned by Base. So we should not commit type piracy and overload hash or equality for it. Does this answer your question?

[sunxd3]

Yes, perfectly.