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functor-combinators v0.3.0.0 Release Notes

  • August 5, 2020

    🚀 https://github.com/mstksg/functor-combinators/releases/tag/v0.3.0.0

    • Data.HBifunctor.Associative, Data.HBifunctor.Tensor: Support for Contravariant and Invariant functor combinators. Main change to the infrastructure: add a FunctorBy associated constraint to Associative to signal what "sort of functor" the tensor supports: it should either be Unconstrained, Functor, Contravariant, or Invariant.
    • Data.Functor.Contravariant.Divise, Data.Functor.Contravariant.Decide, and Data.Functor.Contravariant.Conclude: Temporarily add in the semigroupoidal contravariant typeclasses. These should only be needed until they get merged into semigroupoids.
    • Data.Functor.Contravariant.Divisible: Add free structures for contravariant typeclass hierarchy.

    • Added in some new day convolutions:

      • Data.Functor.Contravariant.Night: Night, a contravariant day convolution using Either, which is the tensor that generates Conclude (and Decidable kinda).
      • Data.Functor.Invariant.Day: Day, an invariant day convolution using tuples.
      • Data.Functor.Invariant.Night: Night, an invariant day convolution using either.

      For the invariant day convolutions, we could write free monoids on them (like Ap/Div/Dec). But instead we just outsource our free structures to Chain, providing useful pattern synonyms and folding functions to pretend like we had an actual free structure.

    • Data.Functor.Combinator: Useful functions in for working with divisible and decidable contravariant functors: divideN, diviseN, concludeN, decideN, divideNRec, and diviseNRec.

    • Contravariant and Invariant instances for many types.

    • Data.HFunctor.Final: FreeOf adjusted to allow for contravariant free types.

    • Data.Functor.Combinator.Unsafe: Add unsafeDivise and unsafeConclude, to mirror the situation with unsafeApply and unsafePlus.