"coordinate" iteration, e.g `(0 to 0)..(1 to 1)` i...

# stdlib

[Hullaballoonatic]

"coordinate" iteration, e.g (0 to 0)..(1 to 1) iterates through 0 to 0, 0 to 1, 1 to 0, 1 to 1. Might be a stretch, but I think it's intuitive.

operator fun Pair<Int, Int>.rangeTo(that: Pair<Int, Int>) = object : Iterable<Pair<Int, Int>> {
    override fun iterator() = object : Iterator<Pair<Int, Int>> {
        var i = [e-mail]
        var j = [e-mail]
        
        val m = that.first - i
        val n = that.second - j

        override fun hasNext() = i <= m && j <= n

        override fun next(): Pair<Int, Int> {
            val res = i to j
            
            if (j == n) {
                j = 0
                i++
            } else {
                j++
            }
            
            return res
        }
    }
}

could also be expanded to higher dimensions with List<Int>.rangeTo(other: List<Int>), IntArray, etc

[Dico]

If anything, this should be a separate type, and I dont think it deserves a place in the stdlib atm. At least it may be difficult to collect all use cases under the same name if so.

[Hullaballoonatic]

Yeah, it's more appropriate for a Vector type, which Kotlin does not have

[Dico]

Kotlin has data class which partially covers the use case of Vector

[karelpeeters]

I'd be happier with a general Cartesian product instead of only for ranges

[karelpeeters]

So (0..1) cart (0..1) but it would also work for other iterables.

[Hullaballoonatic]

yeah, but i do think that the rangeTo operator is a great operator for cartesian product. If they add cartesian product, anyone can create the operator function that calls it should they choose to

operator fun <T> Iterable<T>.rangeTo(other: Iterable<T>) = this cart other

[karelpeeters]

I don't really get what you're saying.

[Dico]

Hes saying he doesn't mind your idea because he can declare his own operator delegating it

[karelpeeters]

Huh so he wants .. to represent cartesian product? Isn't that something different from the code sample, where .. is a kind of specific range-cartesian on pairs?

[Hullaballoonatic]

ah, yeah