I would not recommend looking at Cats without prior Scala experience unless you already have prior experience with a statically typed functional language (such

I would not recommend looking at Cats without prior Scala experience unless you already have prior experience with a statically typed functional language (such as an ML or Haskell). Almost all educational material for Cats assumes at least a basic familiarity with Scala. Any of the books here will be fine: https://docs.scala-lang.org/books.html https://docs.scala-lang.org/books.html. A few are a bit old, but they all get the job done. There's a lack of good coverage for Scala 2.13 (the most recent version), but 2.13 is more or less compatible with 2.11 and 2.12. Its only big change is the collections library, but luckily 2.13's collections library is far simpler than 2.11 and 2.12's and its usage is mostly source compatible. So if you're learning Scala from a 2.12 or 2.11 book and want to make sure you're fine for 2.13, just don't try to understand any complicated CanBuildFrom machinery (which you never really needed to know for 2.11 and 2.12) and just trust that 2.13 has a much simpler approach.