contravariant coyoneda #2150
contravariant coyoneda #2150
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@@ Coverage Diff @@
## master #2150 +/- ##
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+ Coverage 94.67% 94.71% +0.03%
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Files 328 329 +1
Lines 5536 5558 +22
Branches 199 214 +15
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+ Hits 5241 5264 +23
+ Misses 295 294 -1
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| /** `ContravariantCoyoneda[F, ?]` provides a conntravariant functor for any `F`. */ | ||
| implicit def catsFreeCovariantFunctorForCovariantCoyoneda[F[_]]: Contravariant[ContravariantCoyoneda[F, ?]] = |
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Should be Contravariant here
tpolecat
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| final def run(implicit F: Contravariant[F]): F[A] = F.contramap(fi)(k) | ||
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| /** Converts to `G[A]` given that `G` is a contravariant functor */ | ||
| final def foldMap[G[_]](trans: F ~> G)(implicit G: Contravariant[G]): G[A] = |
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can we add a test for this one as well?
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@tpolecat would you like to bring this one into the upcoming 1.1 release? |
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Yeah I'll try to do that test this morning. |
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I added a kind of lame test that exercises |
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@iravid any other feedback on this one? |
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I'm very similar to Kai, the code looks very much okay to me, but I don't quite grasp the use cases, so if we could get one other review, maybe that'd be best. |
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As a practical matter the main use case is factoring out the boilerplate of writing a [stack-safe] contravariant functor. Simple example here. |
This is mostly a copy/paste job from
Coyonedawith the arrows flipped.