cats.free
The dual view of the Yoneda lemma. Also a free functor on F. This is isomorphic to F as long as F itself is a functor. The homomorphism from F[A] to Coyoneda[F,A] exists even when F is not a functor.
F
F[A]
Coyoneda[F,A]
The pivot between fi and k, usually existential.
fi
k
The underlying value.
The transformer function, to be lifted into F by run.
run
Simple function composition.
Simple function composition. Allows map fusion without touching the underlying F.
Converts to F[A] given that F is a functor
Converts to Yoneda[F,A] given that F is a functor
Yoneda[F,A]
The dual view of the Yoneda lemma. Also a free functor on
F
. This is isomorphic toF
as long asF
itself is a functor. The homomorphism fromF[A]
toCoyoneda[F,A]
exists even whenF
is not a functor.