What is the difference between a Monad and a Functor in Haskell?

What is the difference between a Monad and a Functor in Haskell?

In Haskell, a Functor is a type class that allows you to apply a function over wrapped values, while a Monad is a type class that allows for chaining operations on wrapped values. Essentially, all Monads are Functors, but not all Functors are Monads.

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

Sure! A common example of a Functor is the Maybe type. You can use the fmap function to apply a function to the value inside a Maybe, if it exists. For instance, fmap (+1) (Just 2) results in Just 3, while fmap (+1) Nothing results in Nothing.

What about an example of a Monad?

An example of a Monad is the Maybe type again. You can use the >>= operator (bind) to chain operations. For example, Just 2 >>= ( x -> Just (x + 1)) results in Just 3, while Nothing >>= ( x -> Just (x + 1)) results in Nothing.

Why are Monads considered more powerful than Functors?

Monads are considered more powerful because they allow for sequencing operations and handling side effects, while Functors only allow for mapping functions over values. This makes Monads suitable for more complex scenarios like handling state, I/O, or exceptions.