In Scala 3 I can define a functor for state using type lambda: given stateFunctor[S]: Functor[[A] =>> State[S, A]] with override def map[A, B](a: State[S, A])(fx: A => B): State[S, B] = ...

Let's suppose I have a trait with two type parameters, e.g. trait Qux[A, B] and another trait with a higher-kinded type parameter, e.g. trait Turkle[C[_]] I'd like to be able to substitute a ...

I've been digging into FP and everything that surrounds it, and I found the concept of kind projector written somewhere, without details nor explanations. The only thing I found was this github pr...

Consider the following type definition: trait LiftF[F[_], G[_]] { def liftF[A](fa: F[A]): G[A] } When providing a requirement for an implicit of this type in context bounds (using kind projecto...

I have a class Foo with two parameters, and I am trying to write a Functor instance for Foo with the first parameter fixed, as follows: object Scratchpad { trait Functor[F[_]] { def fmap[A, B](...

Taken from typelevel/kind-projector, what's the distinction between: // partially-applied type named "IntOrA" type IntOrA[A] = Either[Int, A] and // type projection implementing the same type a...