solomon-b/monoidal-functors

A library encoding monoidal functors and related structures in Haskell.

monoidal-functors's Issues

QuickCheck Tests

There are many laws related to the classes in this library. It would be great to use QuickCheck to test them.

Not compatible with bifunctors-5.6 , semialign-1.3, semigroupoids-6, transformers-0.6, these-1.2

Compatibility with this version would make it possible to upgrade Stackage

• commercialhaskell/stackage#6910
• commercialhaskell/stackage#6857
• commercialhaskell/stackage#6909

Use template haskell or generics to generate instances.

Improve Haddocks

I have a PR with various haddock improvements but it would be amazing if someone more knowledgeable then myself could help on this task. Examples are especially valuable!

Work out newtype and fundep scheme to avoid instance overlaps

For example:

deriving via FromApplicative (Proxy :: Type -> Type) instance Semigroupal (->) (,) (,) (Proxy :: Type -> Type)
deriving via FromDivisible (Proxy :: Type -> Type) instance Semigroupal (->) (,) (,) (Proxy :: Type -> Type)

deriving via FromAlternative (Proxy :: Type -> Type) instance Semigroupal (->) Either (,) (Proxy :: Type -> Type)
deriving via FromDecidable (Proxy :: Type -> Type) instance Semigroupal (->) Either (,) (Proxy :: Type -> Type)

The instances are indistinguishable because we don't mention the input category in Semigroupal. Unfortunately the reason for this is that the input category doesn't actually occur in the operation of Semigroupal leading to ambiguity which would require tedious type application from our users to resolve. To have are cake and eat it too, we would need to add this input category type parameter to Semigroupal and come up with a system of fundeps so that it would fixed without the use of type applications.