BIOApp

Safe App type that executes a IO. Shutdown occurs after the IO completes, as follows:

• If completed with ExitCode.Success, the main method exits and shutdown is handled by the platform.

• If completed with any other ExitCode, sys.exit is called with the specified code.

• If the IO raises an error, the stack trace is printed to standard error and sys.exit(1) is called.

When a shutdown is requested via a signal, the IO is canceled and we wait for the IO to release any resources. The process exits with the numeric value of the signal plus 128.

 import cats.effect._
 import cats.implicits._
 import monix.bio._

 object MyApp extends BIOApp {
   def run(args: List[String]): UIO[ExitCode] =
     args.headOption match {
       case Some(name) =>
         UIO(println(s"Hello, \${name}.")).as(ExitCode.Success)
       case None =>
         UIO(System.err.println("Usage: MyApp name")).as(ExitCode(2))
     }
 }

N.B. this is homologous with cats.effect.IOApp, but meant for usage with IO.

Works on top of JavaScript as well ;-)