Get Programming with Haskell

Lesson 29. Lists as context: a deeper look at the Applicative type class

After reading lesson 29, you’ll be able to

• Explain the formal definition of the Applicative type class
• Represent parameterized types as either containers or contexts
• Use List as a context to explore nondeterministic computing

In the preceding lesson, you learned how to use the <*> (pronounced app) operator to extend the power of Functor’s <$> (pronounced fmap) operator. In this lesson, you’ll take a closer look at the Applicative type class. You’ll explore the difference between types that represent a container and types that represent a context. You’ll finish by looking at the powerful things you can achieve by using lists as a context.

Consider this ...