The vector library can be called, which is shorthand for vector.pack:
vector(x, y, z) -- same as vector.pack(x, y, z)
Example
local a = vector.pack(1, 2, 3)
local b = vector.pack(5)
print(a + b) --> 6, 7, 8
-- put the 3 numbers from lovr.headset.getPosition into a vector!
local position = vector(lovr.headset.getPosition())