Introduction to ZIO's Built-in Services

ZIO already provides four built-in services:

1. Console — Operations for reading/writing strings from/to the standard input, output, and error console.
2. Clock — Contains some functionality related to time and scheduling.
3. Random — Provides utilities to generate random numbers.
4. System — Contains several useful functions related to system environments and properties.

When we use these services we don't need to provide their corresponding environment explicitly. ZIO provides built-in live version of ZIO services to our effects, so we do not need to provide them manually.

import zio._

import java.io.IOException

object MainApp extends ZIOAppDefault {
  val myApp: ZIO[Any, IOException, Unit] = 
    for {
      date <- Clock.currentDateTime
      _    <- ZIO.logInfo(s"Application started at $date")
      _    <- Console.print("Enter your name: ")
      name <- Console.readLine
      _    <- Console.printLine(s"Hello, $name!")
    } yield ()

  def run = myApp
}