Version: 2.0.x

Console

The 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
`print`	`line: => String`	`ZIO[Any, IOException, Unit]`
`printError`	`line: => String`	`ZIO[Any, IOException, Unit]`
`printLine`	`line: => String`	`ZIO[Any, IOException, Unit]`
`printLineError`	`line: => String`	`ZIO[Any, IOException, Unit]`
`readLine`		`ZIO[Any, IOException, String]`

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

As ZIO data type supports 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._
import zio.Console._

object MyHelloApp extends ZIOAppDefault {
  val program: ZIO[Any, IOException, Unit] = for {
    _    <- printLine("Hello, what is you name?")
    name <- readLine
    _    <- printLine(s"Hello $name, welcome to ZIO!")
  } yield ()

  def run = program
}

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

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