What are monads in Haskell and how do I use them?

What are monads in Haskell and how do I use them?

Monads in Haskell are a way to handle computations in a functional programming style. They allow for chaining operations while managing side effects. The most common monads are Maybe, List, and IO.

Can you give me an example of using the Maybe monad?

Sure! The Maybe monad is used to represent computations that might fail. For example:

safeDivide :: Float -> Float -> Maybe Float
safeDivide _ 0 = Nothing
safeDivide x y = Just (x / y)

This function returns Nothing if the divisor is zero, otherwise it returns the result wrapped in Just.

How do I chain operations with monads?

You can use the >>= operator to chain operations. For example:

result = Just 10 >>= 
    \\x -> safeDivide x 2 >>= 
    \\y -> Just (y + 5)

This chains the operations, passing the result from one to the next.

What are some other common monads I should know about?

Other common monads include the List monad for non-deterministic computations and the IO monad for handling input/output operations. Each has its own unique use cases.