Lesson 3: Laws and orders

Contents
  • Let’s Review
  • Flipped Either
  • The function type
  • More on kinds
  • Function map
  • What isn’t a functor
  • Coming up

In previous lessons, we have looked at some common functors, what their Functor instances look like, and how to use them. This lesson will look at some unusual but important cases of this cornerstone typeclass, as well as some types that are not instances of Functor, which will hopefully lead us to a better understanding of what Functor is about and why it matters so much.

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