true, false, and nil

[alan@... (Alan Watson)]

I keep banging up against the overloaded meaning of nil: something has
no value and something is false.

This overloading causes me problems when I have tables in which a
value can be absent, present and true, or present and false.

Furthermore, Lua is supposed to be useful as a configuration language.
Which of the following do you prefer?

	dothis = true
	dothat = false
	
	dothis = not nil
	dothat = nil

(A false solution to this second problem is to set "true = not nil".
This idea has been explored extensively in C which has a somewhat
similar problem. You end up with situtations where a variable can be
true but not equal to the value of "true", for example, the value "2"
is true, but is not equal to "not nil".)

Can someone persuade me that the current situation is a Good Thing
and that a proper boolean type would not be a great improvement?

Alan Watson