make kotlin's nullables act like scala's option

ScalaOption.kt

package com.frontier45

/**
 * Created by du on 16/01/29.
 */

fun <T1, T2> T1?.map(f: (T1) -> T2): T2? {
    return if (this != null) {
        f(this)
    } else {
        null
    }
}

fun <T> T?.forEach(f: (T) -> Unit): Unit {
    if (this != null) {
        f(this)
    }
}

fun <T> T?.getOrElse(f: () -> T): T {
    return this ?: f()
}