A swift script used to demonstrate stream buffering and flushing

countdown.swift

#!/usr/bin/swift

import Foundation

let arguments = CommandLine.arguments

let startingValue = Int(arguments[1])!

var flush = false
if arguments.count == 3 {
    flush = arguments[2] == "-f" ? true : false
}

countDown(from: startingValue, flush: flush)

func countDown(from count: Int, flush: Bool = false) {
    for i in (1...count).reversed() {
        print(i)
        if flush {
            fflush(stdout)
        }
        Thread.sleep(forTimeInterval: 1.0)
    }
}