Created
May 16, 2018 09:24
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| // F[G[_]] ~> H[_] | |
| type MapNestedK[F[_], G[_], H[_]] = FunctionK[λ[a => F[G[a]]], H] | |
| // This compiles | |
| implicit def flatten[F[_]](implicit F: FlatMap[F]): MapNestedK[F, F, F] = | |
| λ[λ[a => F[F[a]]] ~> F](F.flatten(_)) | |
| // But for some reason this doesn't | |
| implicit def flatten[F[_]](implicit F: FlatMap[F]): MapNestedK[F, F, F] = | |
| λ[MapNestedK[F, F, F]](F.flatten(_)) | |
| // Even though explicit instance creating works | |
| implicit def flatten[F[_]](implicit F: FlatMap[F]): MapNestedK[F, F, F] = | |
| new MapNestedK[F, F, F] { | |
| override def apply[A](fa: F[F[A]]): F[A] = F.flatten(fa) | |
| } |
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The error I get is
not found: value λ