Scala Functor

You might have heard aboutMonad,Monoid,Applicative, etc…

In this episode, we are focusing on theFunctor.

The formal definition for aFunctoris a transformation from a categoryAto a categoryB. Such transformations are often represented by an arrow:A -> B.

This transformation, in Scala, is translated to the methodmapthat we have seen a lot in the past.

AFunctor(F), in category theory, must follow several rules:

• All element ofAmust have a result inB
• Identity:
  • If we defineid, the identity method:id(a) == a,
  • thenid(F) == F.map(id).
• Composition:
  • If we definefandg, two methods,
  • thenF.map(f).map(g) == F.map( g(f(_)) ).

In the following episode, we are going to learn more about the other component of the category theory ecosystem and functional programming overall.