Re: [ANN] Lua 5.2.0 (beta-rc1) now available

[Dmitriy Kryuk <kryukdmitriy@...>]

On 06/16/2011 08:53 PM, Roberto Ierusalimschy wrote:
> > > My vote would be for "label foo" or "foo::". The symmetry looks a bit
> > > ugly to me IMO and looks like it should be some kind of expression
> > > (e.g. |foo| is commonly written in text to mean math.abs(foo)), and !
> > > and&  just seem confusing when they mean different things in other
> > > languages.
> > >        
> > This would be my preference too. Out of interest, would the grammar
> > unambiguously support "stat ::= (label | goto) Name" without having to
> > make label and goto into keywords?
> >      
> Probably (because there are no other meanings for "name name" and Lua's
> parser has full computational power), but it would be messy.
>
> -- Roberto
>
>    
I think if the "goto" operation itself is a part of the core language, 
there is a point in introducing a label as a new datatype, much like a 
function is. If so, it seems appropriate for labels to be declared the 
same way as functions:

label aaa
-- Some code here
goto aaa

Or the same, closer to what it would be internally:

aaa = label
-- Some code here
goto aaa

If so, the "label" operator should be a no-operand, returning some 
internal "address" or whatever used to refer to the next operator inside 
the virtual machine.