adamw

import zio._

object Main extends App {
  override def run(args: List[String]): ZIO[zio.ZEnv, Nothing, ExitCode] = {
    // instead of a method accessor, explicitly accessing the environment
    val program: ZIO[Has[UserRegistration], Throwable, User] =
      ZIO.accessM[Has[UserRegistration]](_.get.register(User("adam", "adam@hello.com")))

    // the DB service is created using through layers (which wrap managed resources)
    val dbLayer: ZLayer[Any, Throwable, DB] = 

adamw

import zio._

object Main extends App {
  override def run(args: List[String]): ZIO[zio.ZEnv, Nothing, ExitCode] = {
    ConnectionPoolIntegration
      .managedConnectionPool(DBConfig("jdbc://localhost"))
      .use { cp =>
        lazy val db = new RelationalDB(cp)
        lazy val userModel = new DefaultUserModel(db)
        lazy val userRegistration = new UserRegistration(DefaultUserNotifier, userModel)

adamw

import zio.Task

trait DB {
  def execute(sql: String): Task[Unit]
}

class RelationalDB(cp: ConnectionPool) extends DB {
  override def execute(sql: String): Task[Unit] =
    Task {
      println(s"Running: $sql, on: $cp")

adamw

import zio._

object Main extends App {
  override def run(args: List[String]): ZIO[zio.ZEnv, Nothing, ExitCode] = {
    // using the UserRegistration's method accessor to construct the program,
    // outside of a layer definition
    val program: ZIO[UserRegistration, Throwable, User] =
      UserRegistration.register(User("adam", "adam@hello.world"))

    // composing layers to create a DB instance

adamw

import zio.{Task, ZIO, ZLayer, ZManaged}

object DB {
  // 1. service
  trait Service {
    def execute(sql: String): Task[Unit]
  }

  // 2. layer
  val liveRelationalDB: ZLayer[HasConnectionPool, Throwable, DB] = ZLayer.fromService 

adamw

import zio.{Task, ZIO, ZLayer}

object UserRegistration {
  // 1. service 
  class Service(notifier: UserNotifier.Service, userModel: UserModel.Service) {
    def register(u: User): Task[User] = {
      for {
        _ <- userModel.insert(u)
        _ <- notifier.notify(u, "Welcome!")
      } yield u

adamw

// UserModel.scala
import zio.{Task, ZIO, ZLayer}

object DB {
  // 1. service
  trait Service {
    def execute(sql: String): Task[Unit]
  }
  
  // 2., 3. omitted here

adamw

package sttp.tapir.examples

import cats.arrow.FunctionK
import cats.data.OptionT
import izumi.reflect.Tag
import org.http4s._
import org.http4s.server.Router
import org.http4s.server.blaze.BlazeServerBuilder
import org.http4s.syntax.kleisli._
import zio.interop.catz._

adamw

package sttp.tapir.examples

import org.http4s._
import org.http4s.server.Router
import org.http4s.server.blaze.BlazeServerBuilder
import org.http4s.syntax.kleisli._
import zio.interop.catz._
import zio.{Has, RIO, Runtime, ZIO, ZLayer}
import org.http4s.dsl.Http4sDsl
import zio.clock.Clock

adamw

package com.softwaremill.test;

import akka.actor.ActorSystem;
import akka.kafka.CommitterSettings;
import akka.kafka.ConsumerMessage;
import akka.kafka.ConsumerSettings;
import akka.kafka.Subscriptions;
import akka.kafka.javadsl.Committer;
import akka.kafka.javadsl.Consumer;
import akka.stream.OverflowStrategy;