Ad-hoc Polymorphism in Cats

Taking a deeper look into how ad-hoc polymorphism works with Scala Cats.

The concept of polymorphism is the ability for a code that can work with multiple types.

TODO What does ad-hoc mean here?

This can be done in many different ways.

Inheritance

TODO Look up Type System

With inheritance, polymorphism is achieved with subclasses.

The OO way. Subclassing.

Java supports inheritance.

We can declare an interface or class with the desired functionality.

Functionality vs Behavior

Functionality - The function Behavior - The implementation of the function

interface Animal {
    public String speak();
}

We can have many forms of speak by implementing the interface.

class Dog implements Animal {
    public String speak() {
        return "woof";
    }
}

class Cat implements Animal {
    public String speak() {
        return "woof";
    }
}

We can also override implemented behavior by subclassing

class BigDog extends Dog {
    public String speak() {
        return "WOOF";
    }
}

This overrides the previous behavior.

The downside

Trait Objects