You should try the Writer monad, which adds an extra value for logging: http://learnyouahaskell.com/for-a-few-monads-more http://learnyouahaskell.com/for-a-few-

You should try the Writer monad, which adds an extra value for logging: http://learnyouahaskell.com/for-a-few-monads-more http://learnyouahaskell.com/for-a-few-monads-more