registry

A small dependency-injection / wiring library for Scala 3.

A Registry is a list of functions and values. The Registry main function, make[T], can be called to make a value of type T by invoking the first function that returns a T. The function parameters are retrieved by recursively calling make on the Registry. That’s it!

import registry.*

case class Host(value: String)
case class Port(value: Int)
case class DbConfig(host: Host, port: Port)
case class App(db: DbConfig)

val r =
  fun[App] +:
    fun[DbConfig] +:
    value(Host("localhost")) +:
    value(Port(5432))

val app: App = r.make[App]
// app: App = App(DbConfig(host = Host("localhost"), port = Port(5432)))

Learn more:

• Getting started install, first registry, make vs makeSafe.

• Concepts how a Registry actually works:
  • Registry and entries the four prepend operators and LIFO precedence.
  • Resolution how make[T] walks the dependency graph.
  • Safety what +: and makeSafe[T] check.
  • Memoization share vs const, …
  • Customization refinements, erase, …
• Modules per-artifact guides:
  • registry the dependency-injection core.
  • registry-cats lift constructors, functions, and values into any Applicative[F]
  • registry-cbor derive borer Encoder[T] / Decoder[T] instances for CBOR.
  • registry-circe derive Encoder[T] / Decoder[T] instances from a registry.
  • registry-scalacheck derive Gen[T] instances from a registry.