Data compatibility in distributed systems is a problem that is often adressed in ad-hoc manners and suffer from bikeshedding. Developing a formal framework for reasoning about it is crucial to ensure a seamless evolution of complex systems and easy inter-connectivity of components.
Disclaimer
This gist talks specifically about backward compatibility rules. Intuitively, forward compatibility rules are the opposite of backward ones.
| package baccata | |
| /** | |
| * Inspired from Grant Beaty's Scunits | |
| */ | |
| trait Bool { | |
| type branch[B,T <: B, E <: B] <: B // typelevel if-then-else | |
| type not <: Bool | |
| type or[R <: Bool] <: Bool | |
| type and[R <: Bool] <: Bool |
| //> using lib "org.http4s::http4s-ember-server:0.23.19" | |
| //> using lib "org.http4s::http4s-dsl:0.23.19" | |
| package foo | |
| import cats.effect._ | |
| import cats.syntax.all._ | |
| import org.http4s.implicits._ | |
| import org.http4s.ember.server._ | |
| import org.http4s._ |
| import org.http4s._ | |
| import org.http4s.syntax.all._ | |
| import smithy4s.kinds._ | |
| import smithy4s.Service | |
| import smithy4s.http4s.SimpleRestJsonBuilder | |
| import cats.data.OptionT | |
| import cats.effect._ | |
| import cats.effect.syntax.all._ | |
| def precompileRoutes[Alg[_[_, _, _, _, _]]](service: Service[Alg])( |
| //> using lib "co.fs2::fs2-core:3.5.0" | |
| import cats.effect.IOApp | |
| import cats.effect._ | |
| import cats.effect.std.Queue | |
| import scala.concurrent.duration._ | |
| import cats.effect.syntax.all._ | |
| import cats.syntax.all._ | |
| import cats.instances.queue | |
| object Main extends IOApp.Simple { |
| //> using lib "org.typelevel::cats-core:2.8.0" | |
| package foo | |
| import cats.Functor | |
| import cats.arrow.FunctionK | |
| import cats.Id | |
| import cats.ApplicativeError | |
| import cats.MonadError | |
| import scala.util.Try | |
| import cats.syntax.all._ |
| import shapeless._ | |
| ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// | |
| // THE IMPLICIT CLASS THAT ALLOWS TO CALL #copy ON ANY SEALED TRAIT INSTANCE | |
| ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// | |
| object copySyntax { | |
| implicit class CopySyntax[TypeToCopy](thingToCopy: TypeToCopy) { |
| //> using lib "org.typelevel::cats-core:2.7.0" | |
| import cats.Applicative | |
| import cats.syntax.all._ | |
| import cats.ContravariantMonoidal | |
| import cats.InvariantMonoidal | |
| import cats.InvariantSemigroupal | |
| import cats.Show | |
| import cats.~> | |
| import cats.arrow.FunctionK | |
| import cats.kernel.Monoid |
| import cats._ | |
| import cats.syntax.all._ | |
| // format: off | |
| /** | |
| * A couple recursion-schemes, named in a less arcanic fashion than usual. | |
| * These functions allow to decouple the recursive aspect of model construction | |
| * and validation, from the domain-specific concerns. | |
| */ | |
| object recursion { |
| import scala.scalajs.js | |
| import scala.scalajs.js.annotation.JSImport | |
| /** | |
| * @see https://nodejs.org/dist/latest-v7.x/docs/api/crypto.html#crypto_crypto | |
| */ | |
| @js.native | |
| trait Crypto extends js.Object { | |
| def createHash(algorithm: String): Hash = js.native |