add as extension method to optics in Scala 2 and 3 #1110
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Changes should be made to Focus too:
- The type signature of the
askeyword should be changed to be consistent with[From, To <: From], which is possible now in RC1 - The implementation of the
AsGeneratorinFocusshould delegate to this external operator functionality, instead of using its own implementation.
| implicit def toMacroFoldOps[From, To](optic: Fold[From, To]): MacroFoldOps[From, To] = new MacroFoldOps(optic) | ||
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| class MacroPrismOps[From, To](private val optic: Prism[From, To]) extends AnyVal { |
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Why do we need an extension per optic type, when have a class hierarchy now?
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That's for narrowing the output type lens.as is an Optional but getter.as is a Fold. There might be another way to do it with transparent, I am not sure.
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Btw, you will note that there is not an extension per Optic type, for example, there is not one Getter, Iso, or Lens as we don't need them to get a more precise return type.
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@kenbot I tried to change the definition of |
For Scala 2, I added extension methods in the macro module which basically do
optic.andThen(GenPrism[To, CastTo]).For Scala 3, I added the same extension methods but in the core module. I could have implemented it by forwarding it to
Focus(_.as[CastTo])but I am worried about the documentation.I mean for
Focusit makes sense to usetransparentbecause the return type may vary but here we know it before hand. Maybe one of you know a way to do it? Admittedly, I am just copy/pasting and tweaking code but I have no good understanding of the macro APIs.TODO in another PR, do the same for
ApplyOptics.