How to typecheck Roblox module objects?

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#1

Let’s say I have an object “human” that has methods and properties and its own module script, a bit like this:

local Human = {}
Human.__index = Human

function Human.new()
	local human = {}
	human.exists = true
	setmetatable(human, Human)
	return human
end

function Human:DoesExist()
	return self.exists
end

return Human

How would I type check said object so that in another module I can do:

function Car:GetHuman(): human
	return self.human
end

Also if possible, correct any bad practices I may be using in this OOP example.

#2

I believe everything would already be typechecked by default, but if you manually want to typecheck your Human class, say to use it across other modules, you just do

-- // modulescript
export type Human = {
  Exists: boolean;
}
-- // another modulescript
local humanClass = require(humanModule)

local a: humanClass.Human = blah

function Human:DoesExist(): boolean
return self.exists;
end

As for bad practices, in your new function, this isn’t really a bad practice but more of just how it’s normally done, but I’d do something like

function Human.new()
  local self = setmetatable({}, Human)
  self.Exists = true
  return self;
end