@hackage / kindly-functors

Revision history for kindly-functors

Upcoming

0.2.0.0 -- 2026-07-26

• Expand GHC support through 9.12. Bump nixpkgs, Cabal, and CI tooling.
• Replace the Makefile with a justfile, including release commands.
• Add a public kindly-functors:laws sublibrary of hedgehog-classes Laws for the functor classes: identity and composition for map1/map2, one bundle per variance, plus Kindly.Rank2.Laws for the rank-2 bmap/bmap2 functors. The test suite law-checks them across the structural and generic-representation instances.
• Replace the ~60 empty per-type MapArg1/MapArg2/MapArg3 instances with three blanket instances in Kindly.Class, keyed on the functor's domain category. A CategoricalFunctor instance no longer needs a paired MapArgN instance. No public API change.
• Fill out the Type -> Type instance coverage in Kindly.Functor: the transformers stack (ReaderT, StateT, WriterT (Lazy/Strict/CPS), ExceptT, MaybeT, IdentityT, ContT, RWST (Lazy/Strict/CPS), AccumT, SelectT, Backwards, Reverse, Constant, Lift), partially-applied profunctors (Star, Costar, Forget), semigroupoids (WrappedApplicative, MaybeApply, Static), These1, Generically1 (base >= 4.17), and the remaining non-phantom Contravariant types from base (Comparison, Equivalence, Op). Adds a direct transformers dependency.
• Add instances for the bifunctors package (new dependency): Flip, Clown, Joker, Product, Sum, Tannen, Biff, and WrappedBifunctor, each with its partial application in Kindly.Functor.
• Add profunctor (Dom = Op) instances for Star, Costar, Forget, Kleisli, and WrappedArrow, and a profunctorLaws bundle to the laws sublibrary. Kleisli, Star, and Forget need no Monad/Functor constraint for map2, unlike their Hask Profunctor instances.
• Add profunctor instances for Procompose, Rift, Yoneda, Coyoneda, and Cayley, with their partial applications in Kindly.Functor.
• Add profunctor instances for the Tambara/Pastro families (plain and Sum), Closure, Environment, FreeTraversing, CofreeTraversing, FreeMapping, and CofreeMapping, with their partial applications in Kindly.Functor. This completes coverage of the profunctors package.
• Add instances for Tagged (new tagged dependency): covariant in its last argument, profunctorial (phantom) in its first.
• Add a bifunctor instance for Op: covariant in its first argument with contravariant partial applications, i.e. Bifunctor (->) Op Op. Hask's Bifunctor and Profunctor cannot express this. Add observedBifunctorLaws for law-testing such instances.
• Add instances for Fix (bifunctors), Constant at two arguments, and Dual (semigroupoids). Add trifunctor instances for Forget and K1, and an observedTrifunctorLaws bundle for map3.
• Add instances for containers (new dependency): Map k, IntMap, Seq, ViewL, ViewR, Tree, and SCC.
• Generalize invmap to functors of any variance and add mapIso, both backed by a new LiftIso class in Kindly.Class that reflects a (->) isomorphism into an arbitrary category. invmap and mapIso now resolve for covariant and contravariant functors, not just invariant ones, dropping the leg the functor cannot use. The domain category is fixed by the functor argument, so existing invariant call sites are unchanged. Add liftIsoLaws and mapIsoLaws bundles to the laws sublibrary. LiftIso instances cover (->), Op, Iso (->), and the Kleisli categories Star f and Kleisli f (for Monad f). Star Maybe is the domain of a Filterable functor.
• Add bimapIso and trimapIso, the bifunctor and trifunctor analogs of mapIso. Each maps a (->) isomorphism through every position of a bifunctor/trifunctor regardless of that position's variance, taking one Iso per position and reflecting it into that position's category with liftIso. Add bimapIsoLaws and trimapIsoLaws bundles to the laws sublibrary. Re-export Iso from Kindly.Functor, Kindly.Bifunctor, Kindly.Trifunctor, and Kindly so callers of mapIso/bimapIso/trimapIso can build isomorphisms without importing Data.Isomorphism directly.
• Give CategoricalFunctor's map a generic default backed by kind-generics, so a datatype with a GenericK instance (from deriveGenericK) gets a CategoricalFunctor instance from an empty body carrying only its Dom and Cod. The default reads variance off the field structure and dispatches on the instance's categories: covariant (Dom = (->)), contravariant (Op), and invariant (Iso (->)) single-parameter functors, and two- and three-parameter functors (bifunctors, profunctors, trifunctors) in any per-argument combination of those variances. A covariant or contravariant instance of the wrong sign is a compile error rather than a wrong answer. Adds a kind-generics dependency.
• Export the deriving via adapters FromFunctor and FromContra from Kindly.Functor, and FromBifunctor and FromProfunctor from Kindly.Bifunctor. A type with an existing base Functor/Contravariant/Bifunctor/Profunctor instance can derive its CategoricalFunctor instance through the matching adapter.

0.1.0.1 -- 2024-02-04

• Initial Release.