Destroy your foldLeft with traverse and State - Scala tutorial

Jakub Kozłowski demonstrates how to refactor complex foldLeft operations in Scala using the State monad and traverse from the Cats library.

In this video, I show how you can tame the complexity of an untamed foldLeft by replacing it with a traverse. If you enjoyed this video, please like and subscribe, and hit the bell icon so you don't miss another one ;) I'm on Twitter: twitter.com/kubukoz on GitHub: github.com/kubukoz sometimes stream on Twitch: twitch.tv/kubukoz And you can buy me a coffee if you want: ko-fi.com/kubukoz Read the code: github.com/kubukoz/videos/blob/main/traverse-with-state/src/… Table of contents: 0:00 - Introduction 0:22 - Overview of the example 2:03 - Refactoring: splitting the function into steps 4:08 - The limitation of function composition, State monad overview 6:35 - Refactoring to the State monad 8:39 - Using traverse 9:49 - Further splitting of State transitions 11:10 - Summary, parting words Useful links: My video on Traverse: youtube.com/watch?v=CSErp1mZodM State chapter in "Scala with Cats": scalawithcats.com/dist/scala-with-cats.html#the-state-monad State documentation in Cats: typelevel.org/cats/datatypes/state.html Red Book (functional programming in Scala) chapter on State: livebook.manning.com/book/functional-programming-in-scala/ch… Exercises for the Red Book: scala-exercises.org/fp_in_scala/pure_functional_state Herding Cats - State datatype: eed3si9n.com/herding-cats/State.html