Exit

Flix provides Exit as a library effect for terminating the program. The Exit effect has a default handler, so no explicit runWithIO call is needed in main. The key module is Sys.Exit.

The Exit Effect

The Exit effect has a single operation that immediately stops the JVM with a given exit code:

pub eff Exit {
    /// Immediately exits the JVM with the specified `exitCode`.
    def exit(exitCode: Int32): Void
}

The return type Void indicates that exit never returns normally.

Exiting the Program

The simplest use of Exit is to terminate with a specific exit code:

use Sys.Exit

def main(): Unit \ { Exit, IO } =
    println("Goodbye!");
    Exit.exit(0)

A zero exit code conventionally signals success, while a non-zero code signals an error.