What are some examples of applicatives in Haskell?

What are some examples of applicatives in Haskell?

Applicatives in Haskell allow you to apply functions wrapped in a context to values wrapped in a context. For example, using the Applicative instance for Maybe, you can combine two Maybe values.

Can you show me a code example?

Sure! Here's a simple example:

import Control.Applicative

add :: Maybe Int -> Maybe Int -> Maybe Int
add x y = (+) <$> x <*> y

result = add (Just 3) (Just 5)  -- This will give Just 8

What if one of the values is Nothing?

If one of the values is Nothing, the result will also be Nothing. For example:

result = add (Just 3) Nothing  -- This will give Nothing

Are there other types that support applicatives?

Yes, many types in Haskell support the Applicative interface, such as lists, Either, and IO. Each has its own behavior.