最初だけとか最後だけとかできるwhile

while2.kt

fun while2Test(){
    var i = 0
    while2({i <= 4}){
        doAny {
            println("any $i")
            i++
        }
        doFirst {
            println("first $i")
        }
        doLast {
            println("last $i")
        }
    }
}

fun while2(bool:()->Boolean, runBlock:While2.()->Unit){
    val while2 = While2()
    while2.apply(runBlock)
    if (bool()) {
        while2.doFirst()
        while2.doAny()
    }
    var isWhileRun = false
    while (bool()) {
        while2.doAny()
        isWhileRun = true
    }
    if (isWhileRun) {
        while2.doAny()
        while2.doLast()
    }

}

class While2{
    var doFirst :()->Unit = {}
    var doLast :()->Unit = {}
    var doAny :()->Unit = {}
    fun doFirst(runFirst:()->Unit){
        doFirst = runFirst
    }

    fun doLast(runLast: () -> Unit){
        doLast = runLast
    }

    fun doAny(runAny:()->Unit){
        doAny = runAny
    }
}