Re: How can one decide between 'not set' and 'not existing?

[Coda Highland <chighland@...>]

On Wed, Jul 25, 2012 at 9:46 PM, Jay Carlson <nop@nop.com> wrote:
> On Jul 25, 2012, at 5:09 PM, Coda Highland wrote:
>
>> On Wed, Jul 25, 2012 at 2:02 PM, Dimiter 'malkia' Stanev
>> <malkia@gmail.com> wrote:
>>> -- "function() end" would gurantee an unique value, differentiated from
>>> others, unless the VM merges it under one umbrella. Even them, maybe reusing
>>> coroutine might return you an unique value for the lifetime of the
>>> application (or something even simpler)
>>
>> Unless I miss my guess, the VM couldn't merge it because they'd have
>> different upvalues.
>
> There are no free variables in function() end and hence no upvalues, so it certainly could be merged/hoisted to chunk level.

Oh right. Silly me.

> Use NULL={} instead. List constructors guarantee uniqueness.

*nods* And tables have reference equality only, so that's completely sufficient.

/s/ Adam