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Lens (optics) library module?

Issue #36 resolved
Jean-Baptiste Giraudeau created an issue

I'm putting together a lens library (adapted from fj) based on fugue data types: https://github.com/javafp/fugue-optics (work in progress)

was thinking that maybe it could better be a fugue sub-module than a separate project. Would you be interested in a pull request?

Comments (13)

  1. Anund McKague

    I like the idea. Let me have a look at fugue-optics later today before you put to much effort into moving things around.

  2. Jed Wesley-Smith

    that looks great, would be fantastic to have it as a fugue module!

    there would be a few things to do before it could be accepted though. Most specifically we need a high degree of test coverage for all fugue code, so we'd need a comprehensive test suite. Secondly, I think it point out the need for Semigroup and Monoid classes, I'd prefer to have those so we can describe a lawful Fold.foldMap for instance (although, BinaryOperator maybe enough for Semigroup, but it doesn't specify associativity).

  3. Jean-Baptiste Giraudeau reporter

    I agree that monoid and semigroup would be better. And I also think that laws would be best checked with property-based testing. Which framework should be used for fugue? scalacheck? functionaljava-quickcheck? junit-theories? functionaljava-quickcheck would be my perference.

  4. Jed Wesley-Smith

    I'd vote for scalacheck, it is probably the most powerful and we already have the scala module.

  9. Jean-Baptiste Giraudeau reporter

    I should be able to get back at this next week.

    I've been busy with another (related) project: Derive4J (it has support for fugue2/fugue3 btw). One of the main objectives of the project is to be able to generate lens/prism/optional at compile time.

  10. Jed Wesley-Smith

    oh, derive4j looks great! Apart from anything else, it's a really practical example of using object-algebras, good stuff!

  11. Jean-Baptiste Giraudeau reporter

    Yes a special kind of object-algebra. as such it give some support for extensibility: you can extends a Cases visitor (add cases) and create another ADT out of it. And visitor instances for the new ADT would also be able to visit the original one.

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