Effective Haskell

Running IO in Real Applications

At the beginning of this chapter, you learned about laziness and what that means for performing IO in Haskell applications. After that we looked at several small examples of how to work with IO in Haskell, building up more complex IO actions from smaller ones and creating programs that have useful side effects. Although the examples we looked at should have helped you gain an intuition for working with IO, so far we’ve managed to get away with avoiding having to understand too much about the details of how IO is working, and without having to think too much about the performance of our application. In Haskell applications that do a lot of IO, it’s likely that sooner rather than later you’ll encounter a scenario ...