To return a value from a function or method in Haskell, we use the return keyword. The return keyword can be used in any function to return a value of a specific type.
Here's an example of a simple function that returns a value:
addNumbers :: Int -> Int -> Int
addNumbers x y = x + y
In this code, the addNumbers function takes two integer arguments and returns their sum as an integer. The return keyword is not explicitly used here, but the function body implicitly returns the integer value.
Here's an example of a function that uses the return keyword:
calculateArea :: Double -> Double -> Double
calculateArea l w = return (l * w)
In this example, the function calculates the area of a rectangle given its length and width. The return keyword is used to explicitly return the calculated value of the area.
It's worth noting that the return keyword is optional in Haskell functions. In the absence of the keyword, Haskell uses lazy evaluation to automatically return the result of the last expression in the function body.