arrow-kt
Profunctor optics
Optics with a different likely more powerful encoding.
This is pretty complete feature wise, however it is not well tested, documented and benchmarked. My thoughts behind opening this pr now are to gather feedback on the api + its internals before I get onto further testing/benchmarking and documenting,
As for how it all works: There is quite a bit of documentation on the Optic interface and the Profunctor typeclass which should hopefully help to understand the inner workings.
I also had to introduce combineLazy to monoids simply because I have some monoid instances that benefit from laziness (such as Monoid.first. Laziness is decided at the point of invoking a terminal operator and isn't usually a user decision, for example firstOrNull uses eval to avoid too much work on traversals, but sum will use a non-eval traversal which should be faster. This boils down to traverseLazy/traverse and foldLazy/fold (plus their indexed variants).
This implementation comes from the haskell optics package, tho has seen some changes, since kotlin makes variance a lot easier.
The ixcompose method for Optic also has 13 type parameters which I believe could be a new arrow record ignoring tuple/zipN definitions! :laughing:
See https://github.com/arrow-kt/arrow/blob/jo-profunctor-optics/arrow-libs/optics/arrow-optics-profunctor/src/jvmMain/kotlin/test.kt for some examples of the api.
It's been more than a year since the last commit here; is it OK to close this PR?
It's been more than a year since the last commit here; is it OK to close this PR?
Yeah, afaik we have a different optics implementation anyway. Imo profunctor optics are really really nice to work with, but that's in haskell, where they play nice with type inference and have decent performance.