Typeclasses laws #112
Typeclasses laws #112
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raulraja
commented
Jun 15, 2017
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raulraja
commented
- FunctorLaws
- ApplicativeLaws
- MonadLaws
- MonadErrorLaws (deferred to another PR since there is missing instances)
| @@ -1,6 +1,6 @@ | |||
| package katz | |||
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| class EitherMonad<L> : Monad<EitherF<L>> { | |||
| open class EitherMonad<L> : Monad<EitherF<L>> { | |||
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Why does this class need to be open? Could it be an Interface instead?
| @@ -3,14 +3,14 @@ package katz | |||
| typealias KleisiTKind<F, A, B> = HK3<Kleisli.F, F, A, B> | |||
| typealias KleisiF<F> = HK<Kleisli.F, F> | |||
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I believe these two are misnamed too. Could you please use this diff to rename them to Kleisli?
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| object FunctorLaws { | ||
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| inline fun <reified F> laws(AP: Applicative<F> = applicative<F>()): List<Law> = |
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why use an Applicative here, if we are testing Functor laws here? should it be convenient use Functor instead of Applicative ins't it?
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We can't create instances in the generator unless we create a specific typeclass for pure or apply since that is defined in Applicative and that is what we need to lift values into F[_]
| M.flatMap(fa, { M.pure(it) }) == fa | ||
| }) | ||
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| inline fun <reified F> kleisliLeftIdentity(M: Monad<F> = monad<F>()): Unit = |
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one question,
why in MonadLaws have the particular case for Kleisli Monad and not split into MonadLaws and KleisliLaws that have all the MonadLaws plus those 2 specific test?
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Because Kleisli applies to all monads.
https://en.wikipedia.org/wiki/Kleisli_category
In category theory, a Kleisli category is a category naturally associated to any monad T. It is equivalent to the category of free T-algebras.
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@kategory/maintainers I suggest we merge this now since master is already broken in many ways and this proofs some of the types that need immediate action |
* Suspend fx * Code review
