Re: In praise of 'nil' (Was: Proposal for table length operator

["Juris Kalnins" <juris@...>]

On Wed, 15 Dec 2010 09:31:57 +0200, Dirk Laurie <dpl@sun.ac.za> wrote:

> On Wed, Dec 15, 2010 at 08:54:59AM +0200, Axel Kittenberger wrote:
> > >    What happened before the Big Bang?  Nil.
> >
> > As empiricist I must say, no. We don't know. Might been Nil, might
> > been something else. Currently no way to guess.
> Exactly my point, actually.
>
> "nil" in lua means "not one of the possibilities that we know
> something about".  There is no distinction between something unknown
> and something non-existent.

In Lua, almost. Example (5.2):

print(table.pack((function()return end)()).n) -- 0
print(table.pack((function()return nil end)()).n) -- 1
print(table.pack((function()return nil, nil end)()).n) -- 2

If 'nil' was to really be indistinguishable from "non-existent", all three
would have to print '0'.