Effective Haskell

Types and Kinds

Before we can start building out large type level programming examples, we need to spent some time looking at two of the most basic building blocks of type level code: types and kinds. In type level code, the types are the values that we are computing with, and the kinds of those types give us “type” safety in the same way types provide safety to our term level code. Although you’ve worked extensively with types in this book, and you’ve encountered kinds occasionally, the way that we work with them in type level code is frequently different from how we’d work with them in term level code. In this section, we’ll look at how to work with types and kinds for type level code, and see some examples of types and kinds that you wouldn’t ...