What are some fun exercises to practice Haskell functors?

What are some fun exercises to practice Haskell functors?

Here are a few exercises you can try:

1. Implement the Functor type class for a custom data type.
2. Create a function that applies a function to a list of functors.
3. Explore the Maybe type and write functions that utilize its functor capabilities.

Can you explain what a functor is in Haskell?

Sure! In Haskell, a functor is a type class that allows you to apply a function over wrapped values. It must implement the fmap function, which takes a function and a functor, applying the function to the value inside the functor.

What is the difference between a functor and a monad?

Great question! A functor allows you to apply a function to a value wrapped in a context, while a monad provides additional capabilities, such as chaining operations and handling side effects. Monads can be seen as a more powerful abstraction built on top of functors.

Can you give me an example of using fmap?

Absolutely! If you have a Maybe Int value, you can use fmap to apply a function like (+1) to the value inside:

fmap (+1) (Just 5)  -- This will result in Just 6
fmap (+1) Nothing   -- This will result in Nothing