Free, open source books on Scala and functional programming:
Learn to write robust, performant, idiomatic Scala. A focused guide for established developers.
Scala with Cats
Dive deep into functional patterns using Scala and Cats. For experienced Scala developers.
The Type Astronaut's Guide to Shapeless
Scrap your boilerplate and derive type classes with shapeless. For experienced Scala developers.
Learn to use the Play web framework to build web sites and services. For new to intermediate Scala developers.
Learn to use Lightbend's Slick to interact with relational databases. For new to intermediate Scala developers.
Learn functional programming with pictures! A fun and practical introduction for new developers.