hard_deps.lua

deps = {
	A = {"B", "E"},
	B = {},
    C = {"A"},
    D = {"C"},
    E = {"D"}
}
local status = {}
local load_order = {}
function depends(mod, dependant)
    if status[mod] == "loading" then
        local cycle = {}
        while dependant do
            table.insert(cycle, dependant.mod)
            dependant = dependant.dependant
        end
        error("circular dependency: " .. mod .. " <- " .. table.concat(cycle, " <- "))
    end
    if status[mod] == "loaded" then return end
    status[mod] = "loading"
    for _, hard_dep in pairs(deps[mod]) do
        depends(hard_dep, {mod = mod, dependant = dependant})
    end
    status[mod] = "loaded"
    table.insert(load_order, mod)
end
for mod in pairs(deps) do
    depends(mod)
end
print(table.concat(load_order, ", "))