The `@extension` export the extension functions fr...

# arrow

[AdrianRaFo]

The @extension export the extension functions from a type class

interface Functor<F> {
  fun <A, B> Kind<F, A>.map(f: (A) -> B): Kind<F, B>
}

to inheritors

@extension interface IOFunctor : Functor<ForIO> {
  override fun <A, B> Kind<ForIO, A>.map(f: (A) -> B): IO<B> =
    fix().map(f)
}

[Imran/Malic]

is the map function in IOFunctor generated or not

[AdrianRaFo]

It's not, the annotation just give you the ability to get and override the extension function declared on the interface

[Imran/Malic]

Meaning, if I am composing multiple type classes into one. I always use @extension and when my type classes operate over HKT I also add @higherkinds or is it not necessary

[AdrianRaFo]

it is

[Imran/Malic]

thank you