4 Extracting calculations from actions


In this chapter

  • Observe how information enters and leaves a function.
  • Discover functional techniques to make code more testable and reusable.
  • Learn how to extract calculations from actions.

In this chapter, we’re going to do a lot of refactoring. We’re going to look at an existing piece of software, add some features, and then refactor calculations out of the actions. This improves the reuse and testability of the code.

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