Version: 1.0.18

Console

Console service contains simple I/O operations for reading/writing strings from/to the standard input, output, and error console.

Function	Input Type	Output Type
`putStr`	`line: => String`	`URIO[Console, Unit]`
`putStrErr`	`line: => String`	`URIO[Console, Unit]`
`putStrLn`	`line: => String`	`URIO[Console, Unit]`
`putStrLnErr`	`line: => String`	`URIO[Console, Unit]`
`getStrLn`		`ZIO[Console, IOException, String]`

All functions of console service are effectful, this means they are just descriptions of reading/writing from/to the console.

As ZIO data type support monadic operations, we can compose these functions with for-comprehension which helps us to write our program pretty much like an imperative program:

import java.io.IOException

import zio.ZIO
import zio.console._

object MyHelloApp extends zio.App {
  val program: ZIO[Console, IOException, Unit] = for {
    _ <- putStrLn("Hello, what is you name?")
    name <- getStrLn
    _ <- putStrLn(s"Hello $name, welcome to ZIO!")
  } yield ()

  override def run(args: List[String]) = program.exitCode
}

Note again, every line of our program are descriptions, not statements. As we can see the type of our program is ZIO[Console, IOException, Unit], it means to run program we need the Console service as an environment, it may fail due to failure of getStrLn and it will produce Unit value.

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