What is a Functor in Haskell?

What is a Functor in Haskell?

A Functor in Haskell is a type class that allows you to apply a function over wrapped values, like lists or Maybe types.

Can you give me an example of a Functor in action?

Sure! For instance, if you have a list [1, 2, 3] and you want to add 1 to each element, you can use fmap: fmap (+1) [1, 2, 3] results in [2, 3, 4].

What are the laws that Functors must follow?

Functors must satisfy two laws: the identity law (fmap id = id) and the composition law (fmap (f . g) = fmap f . fmap g).

How do I create my own Functor instance?

To create your own Functor, you need to define the fmap function for your type. For example, for a custom type, implement fmap to apply a function to the wrapped value.