Pure Lua Quicksort

-- função que retorna "true" se o elemento A for logicamente menor que B
local comp = function(a, b)
    return a <= b
end

function quicksort(arr, left, right)
    function partition(arr, left, right, index)
        local pivot = arr[index], _index = left
        arr[index], arr[right] = arr[right], arr[index]

        for i = left, right - 1 do
            if comp(arr[i], pivot) then
                arr[i], arr[_index] = arr[_index], arr[i]
                _index = _index + 1
            end
        end
        arr[_index], arr[right] = arr[right], arr[_index]
        return _index
    end

    if right > left then
        local new_index = partition(arr, left, right, (left + right) / 2)
        quicksort(arr, left, new_index - 1)
        quicksort(arr, new_index + 1, right)
    end
end

function quicksort(arr)
    quicksort(arr, 1, #arr)
end

array = { 1, 5, 2, 17, 11, 3, 1, 22, 2, 37 }

quicksort(array)

for _, v in pairs(array) do
    print(v)
end