Summary

In this chapter, we introduced the basic ideas of type-driven development and critically analyzed a piece of dynamically-typed code to explore its potential error conditions that would be prevented by adding static types. We also introduced the ReasonML language and its ecosystem, set up our own Reason project, and got a glimpse of how it can compile statically typed code to JavaScript.

The next chapter will be an important one—we'll delve more into types, values, and working in Reason. See you there!