Not 100% sure on this, but I think you just need to call it conf.lua and have it in the same folder as main.lua and it should work without having to call require yourself.
Since conf.lua is loaded before main.lua is (and by that time, the modules would have been loaded), you can't exactly define the conf function in main.lua... what you can do though, is defer window creation from conf.lua to somewhere else (like love.load in your main.lua or wherever):
-- In conf.lua (I'm leaving out stuff...)
t.window = false -- Don't create a graphical window just yet...
-- In another file, let's say main.lua for example
function love.load(args)
-- Create the window
love.window.setMode(800, 600, {vsync=false})
end
This is neat if you need to parse stuff after conf.lua and only create the window after, based on that data... meaning it won't flash the window twice this way, which would be annoying.
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