luaTarget: "5.1" polyfills #157

Hey,

Since the generated lua code may contain features that are not present in Lua 5.1, there might be a need for Lua polyfills, namely the table.pack and table.unpack methods (of which neither are available in Lua 5.1).

For example

// zoo() actually returns an array we want to unpack. 
// Otherwise we could use /** !TupleReturn */ decorator!
let [foo, bar] = zoo();

Results in

local foo,bar=table.unpack(zoo())

Which won't work in a strict Lua 5.1 environment.

Proposed polyfills

table.pack

if not table.pack then
    function table.pack (...)
        return {n=select('#',...); ...}
    end
end

Source: https://github.com/stevedonovan/Penlight/blob/master/lua/pl/compat.lua#L133

table.unpack

if not table.unpack then
    function table.unpack(...)
        return unpack(...)
    end
end