Mastering Functional Programming

Abstract methods

Let's take a look at the value member section of the Scaladoc documentation of the Monad implementation by Cats. The abstract members section is the most important section of any type cause definition. A type class is a declaration of certain tools, and its concrete instances must support these tools. They are declared, but not implemented in the type class trait. So, the abstract methods defined by a type class constitute a definition of this type class.

Concretely, in the case of Monad, we have three abstract methods, as follows:

• There is a flatMap method, which we are already familiar with.
• The pure method is able to lift any value into an effect type of F.
• There is a tailRecM and type class. It is a tail recursive Monadic ...