Feature request: support sum type in macwire.

Start by tracing the wire[...] entry points and the MainAppInjected example to understand how dependencies are currently resolved. Define how sum-type or environment bindings should be represented and composed, then verify that the requested Scala 3 usage pattern compiles and supports the shown dependency graph.

As the code show in gitter

trait DesuConfigModel:
  val configIO: IO[DesuConfig] = ???
end DesuConfigModel

trait AppConfig(config: DesuConfig):
end AppConfig

trait DoobieDB(config: DesuConfig):
  private val dsConfigIO = IO(config.mysqlDesuQuillDB.dataSource)
  val transactor: Resource[IO, HikariTransactor[IO]] = ???
end DoobieDB

trait FileFinder(appConfig: AppConfig, xa: Transactor[IO]):
  // code
end FileFinder

trait AppRoutes(fileFinder: FileFinder, appConfig: AppConfig):
  // code
end AppRoutes

val configModel = wire[DesuConfigModel]
val appRoutes: Resource[IO, AppRoutes] = for
  desuConfig  <- Resource.eval(configModel.configIO)
  appConfig    = wire[AppConfig]
  doobieDB     = wire[DoobieDB]
  xa                <- doobieDB.transactor
yield
  val fileFinder = wire[FileFinder]
  wire[AppRoutes]

Macwire can support wire in F[_] like distage. Since implicit value and constructor value is fetched by type. You can declare a implicit value like

implicit val implicitVarName = constructorVarName

Here request a feature that support sum type in macwire like zio.ZEnvironment. Then we can support something like distage's Module include(simple version) in Scala2 and Scala3.(distage doc)

Here is the code also in gitter

class DesuConfigModelImpl extends DesuConfigModel

class AppConfigImpl(using DesuConfig) extends AppConfig(summon)

class DoobieDBImpl(using DesuConfig) extends DoobieDB(summon)

class FileFinderImpl(using AppConfig, Transactor[IO]) extends FileFinder(summon, summon)

class AppRoutesImpl(using FileFinder, AppConfig) extends AppRoutes(summon, summon)

import zio.{IO as _, *}

object MainAppInjected:

  type ProjectEnvModule1 = DesuConfig & AppConfig & Transactor[IO]

  given [T: Tag, S <: T](using ZEnvironment[S]): T = summon[ZEnvironment[S]].get

  val envResource: Resource[IO, ZEnvironment[ProjectEnvModule1]] = for
    given DesuConfig     <- Resource.eval((new DesuConfigModelImpl).configIO)
    given AppConfig       = new AppConfigImpl
    doobieDB                 = new DoobieDBImpl
    given Transactor[IO] <- doobieDB.transactor
  yield ZEnvironment(implicitly[DesuConfig], implicitly[Transactor[IO]], implicitly[AppConfig])

  val appRoutes: Resource[IO, AppRoutes] = for
    given ZEnvironment[ProjectEnvModule1] <- envResource // distage include(simple version)
  yield
    given FileFinder = new FileFinderImpl
    new AppRoutesImpl

end MainAppInjected

It circuitously performs the macwire function I imagined use Scala3 and zio.ZEnvironment.