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 design pattern used to handle side effects and manage computations. They allow you to chain operations together in a functional way. The most common monads are Maybe, Either, 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. Here's a simple example:

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

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

How do I chain operations using the Maybe monad?

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

result = safeDivide 10 2 >>= 
 -> safeDivide r 5

This will safely divide 10 by 2, and then take the result and divide it by 5, returning a Maybe value.

What are some other common monads in Haskell?

Other common monads include the Either monad for error handling, the List monad for non-deterministic computations, and the IO monad for input/output operations. Each serves a unique purpose in managing different types of computations.