from lang import clock
from math import floor

def reverse_list(list)
	count = floor(list.length / 2)
	for i in 0..count
		last_index = list.length - i - 1
		last = list[last_index]
		list[last_index] = list[i]
		list[i] = last
	end
	return list
end

N = 20000000
l = (0..N).as_list

start = clock()
reverse_list(l)
print('elapsed: ', clock() - start, 's')