IOApp

App type that runs a cats.effect.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.IO
import cats.effect.concurrent.{ExitCode, IOApp}
import cats.implicits._

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

Source: IOApp.scala

Linear Supertypes

AnyRef, Any

Abstract Value Members

abstract def run(args: List[String]): IO[ExitCode]

Produces the IO to be run as an app.
Produces the IO to be run as an app.
returns
the cats.effect.ExitCode the JVM exits with

Concrete Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
def equals(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def hashCode(): Int

Definition Classes
AnyRef → Any
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
final def main(args: Array[String]): Unit

The main method that runs the IO returned by run and exits the JVM with the resulting code on completion.
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
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final def notifyAll(): Unit

Definition Classes
AnyRef
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
implicit def timer: Timer[IO]

Provides an implicit timer instance for the app.
Provides an implicit timer instance for the app.
On the JVM, the default lazily constructed from the global execution context. Override to avoid instantiating this execution context.
On scala.js, the default is Timer.global.

Attributes
protected
def toString(): String

Definition Classes
AnyRef → Any
final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

Related Doc: package effect

trait IOApp extends AnyRef

Abstract Value Members

abstract def run(args: List[String]): IO[ExitCode]

Concrete Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

final def main(args: Array[String]): Unit

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

final def synchronized[T0](arg0: ⇒ T0): T0

implicit def timer: Timer[IO]

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from AnyRef

Inherited from Any

Ungrouped