How does dependency injection work in Scala without frameworks?

Scala uses typeclasses, reader pattern, and implicits/givens for DI without frameworks.

Instead of runtime DI frameworks, Scala often uses functional dependency injection patterns. The Reader monad passes dependencies explicitly but composably. Implicits (Scala 2) and givens (Scala 3) provide compile-time resolution of dependencies. ZIO introduces environment-based DI with type safety.