let xSorted = List.toArray l
let ySorted = List.toArray l
Array.sortInPlaceWith cmpX xSorted
let xSorted = List.toArray l
let ySorted = List.toArray l
Array.sortInPlaceWith cmpX xSorted
let upRegion = { currentRegion with minY = splitValue }
(valuesInRegion downRegion part1) @ (valuesInRegion upRegion part2)
let upRegion = { currentRegion with minY = splitValue }
(valuesInRegion downRegion part1) @ (valuesInRegion upRegion part2)