How do you return two values from a single method?

Question

When your in a situation where you need to return two things in a single method, what is the best approach?

I understand the philosophy that a method should do one t

Answer 1

Haskell also allows multiple return values using built in tuples:

sumAndDifference        :: Int -> Int -> (Int, Int)
sumAndDifference x y    = (x + y, x - y)

> let (s, d) = sumAndDifference 3 5 in s * d
-16

Being a pure language, options 1 and 2 are not allowed.

Even using a state monad, the return value contains (at least conceptually) a bag of all relevant state, including any changes the function just made. It's just a fancy convention for passing that state through a sequence of operations.