What's the reason behind making `Iterable`'s only ...

# stdlib

[Thomas]

What's the reason behind making `Iterable`'s only constructor a higher order function with an Iterator producer, instead of a simple function that takes a single Iterator?

[Thomas]

Code in question (Kotlin 1.9.21):

/**
 * Given an [iterator] function constructs an [Iterable] instance that returns values through the [Iterator]
 * provided by that function.
 * @sample samples.collections.Iterables.Building.iterable
 */
@kotlin.internal.InlineOnly
public inline fun <T> Iterable(crossinline iterator: () -> Iterator<T>): Iterable<T> = object : Iterable<T> {
    override fun iterator(): Iterator<T> = iterator()
}

[Thomas]

Why isn't it simpler, like:

public fun <T> Iterable(iterator: Iterator<T>): Iterable<T> = object : Iterable<T> {
    override fun iterator(): Iterator<T> = iterator
}

[Thomas]

oh and to be fair I probably shouldn't call it a constructor 👀

[jw]

Iterators are one-shot. Iterables are many-shot.

[Thomas]

ah right that makes sense, thanks