Better support module types when bundling

[jeparlefrancais]

Use a different approach when generating code for the bundle.

Instead of using a single load function which is very loosely type, generate code which keeps the appropriate returned type for each module.

[Stefanuk12]

Possible solution

There are a caveat with this solution. The type casts are mandatory. The issue here is the cache table. Luau refuses to let you index a, and even though it knows the members of the cache table, it either thinks it's empty or type mismatch due to a "missing field".

The ideal solution would be metatable-less, please let me know if you have any better ideas.

local __MODULES__ = {
    cache = {} :: { [string]: any }
}

do
    function __MODULES__.a()
        return {a = 1}
    end
    function __MODULES__.b()
        return {b = 1}
    end
end

do
    function __MODULES__.load_a(): typeof(__MODULES__.a())
        if __MODULES__.cache["a"] then
            return __MODULES__.cache["a"] :: any
        end
        local a = __MODULES__.a()
        __MODULES__.cache.a = a
        return a
    end
    function __MODULES__.load_b(): typeof(__MODULES__.b())
        if __MODULES__.cache["b"] then
            return __MODULES__.cache["b"] :: any
        end
        local b = __MODULES__.b()
        __MODULES__.cache.b = b
        return b
    end
end

local module_a = __MODULES__.load_a()
local module_b = __MODULES__.load_b()