Small general-purpose extension functions and utilities for Kotlin

KotlinUtils.kt

/**
 * If [assumed] is non-null, converts it to a non-null type and executes [block] on the non-null
 * type as an extension function (like with() in the Standard kotlin library)
 *
 * Similar to Swift's "if let = ..." construct.
 */
fun <T> if_let(assumed : T?, block : T.() -> Unit) {
    if (assumed == null)
        return

    val definite : T = assumed
    definite.block()
}

/**
 * Returns the index of [element] in the list, or [default] if the list does not contain [element].
 */
fun <T> List<T>.indexOfOrDefault(element: T, default : Int) : Int {
    val index = indexOf(element)
    return if (index != -1) index else default
}