How to fix this unpack issue?

Question

I'm creating an Array class that adds more usage to tables. I have a metamethod that allows me to combine two tables, ex:

Array(5) .. Array(6, 10) should give you {5, 6, 10}

I'm aware that I can use two loops to do this, but I'm trying to make my code as clean and efficient as possible. I ran into an issue with unpack. I'm trying to concatenate two tables, but it's not including all of the values. Here is my code and output:

local Array = {}
Array.__index = Array

function Array.__concat(self, other)
    return Array.new(unpack(self), unpack(other))
end

function Array:concat(pattern)
    return table.concat(self, pattern)
end

function Array.new(...)
    return setmetatable({...}, Array)
end

setmetatable(Array, {__call = function(_, ...) return Array.new(...) end})

local x = Array(5, 12, 13) .. Array(6, 9) --concatenate two arrays
print(x:concat(", "))

OUTPUT: 5, 6, 9 (I want it to be "5, 12, 13, 6, 9")

Answer 1

This is standard Lua behavior: in an enumeration of function calls separated by commas, only the last one can return multiple results. For instance:

> function f() return 1, 2, 3 end
> print(f(), f())
1    1    2    3

If I were you I would do the simple thing and use a for loop.