Add *Functions traits for all typeclasses, mixed into Prelude.
#1814
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| with ct.InvariantFunctorFunctions | ||
| with ct.PhantomFunctions | ||
| with ct.TraversableFunctions | ||
| extends AnyRef |
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What's the benefit of extending AnyRef here?
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If we add a new package that is alphabetically before algebra, we don't need to change the line algebra.AlgebraFunctions to add it here.
| package algebra | ||
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| trait MonoidFunctions { | ||
| @inline final def empty[A](implicit A: Monoid[A]): A = |
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yep. I'll propose mempty and mappend.
| )(implicit F: Profunctor[F]): F[C, D] = | ||
| F.dimap(fab)(ca)(bd) | ||
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| /* TODO: these clash with the bifunctor versions. Decide on a name for them. |
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contramap / comap
inMap / outMap
mapIn / mapOut
| package ct | ||
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| trait ChoiceFunctions { | ||
| @inline final def leftchoice[F[_, _], A, B, C](fab: F[A, B])(implicit F: Choice[F]): F[A \/ C, B \/ C] = |
| bt: B => T | ||
| )(implicit F: Bifunctor[F]): F[S, T] = | ||
| F.bimap(fab)(as, bt) | ||
| @inline final def lmap[F[_, _], A, B, S](fab: F[A, B])(as: A => S)(implicit F: Bifunctor[F]): F[S, B] = |
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Another option is to call these firstMap, secondMap after Strong (first/second).
| import data.~> | ||
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| trait ApplicativeFunctions { | ||
| @inline final def pure[F[_], A](a: A)(implicit F: Applicative[F]): F[A] = |
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pure vs point. Decisions, decisions.
| have nowhere better to go. This should be made a | ||
| superclass of `FooClass`'s companion object, to ensure | ||
| that the instances are in the correct implicit scope. | ||
| - Note that this means that all typeclass methods must have unique names! |
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@hrhino Some much needed changes here! 🙏 |
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Sounds good. I'll make those changes and rebase once #1825 lands. |
| - `FooClass`: The definition of the typeclass. | ||
| - `FooSyntax`: Syntax macros for the typeclass methods. | ||
| - `FooFunctions`: A trait containing the typeclass's methods, but with | ||
| the typeclass as a type parameter. |
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as an implicit parameter?
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Thanks. I originally had a confusing attempt to say "with the typeclass instance as a type parameter" or something but I trashed it as insufficiently clear.
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@hrhino Landed! |
No exceptions here. Methods like `pure`, which do not allow for `F` to be inferred from the argument types, also get a `*0` variant that uses the "partially applied" hack. A few methods are also exported as natural transformations, named `*NT`, as I saw fit. `*Functions` traits have been set up for all of the subpackages that contain typeclasses, and *those* now get mixed into `Prelude`, to keep it shorter. I have used `F` and `A` as type parameters throughout, irrespective of the type parameters on the actual typeclass. We should sort that out.
No exceptions here. I know at least a few people said they would be interested in this.
Methods like
pure, which do not allow forFto be inferred from the argument types, also get a*0variant that uses the "partially applied" hack. A few methods are also exported as natural transformations, named*NT, as I saw fit.*Functionstraits have been set up for all of the subpackages that contain typeclasses, and those now get mixed intoPrelude, to keep it shorter.I have used
FandAas type parameters throughout, irrespective of the type parameters on the actual typeclass. We should sort that out.