First class : (was Re: Regarding the name 'pairs')

[Mark Hamburg <mark@...>]

On Sep 14, 2009, at 5:26 AM, steve donovan wrote:

> On Mon, Sep 14, 2009 at 2:16 PM, Luiz Henrique de Figueiredo
> <lhf@tecgraf.puc-rio.br> wrote:
> > One important reason for not having "set:values" is that it'd be  
> > sugar
> > for "function (...) return set:values(...) end" and this would imply
> > the creation of a hidden closure.
>
> Yes, it did feel like an incompatible proposal.
>
> So, is there some support for Mark Hamburg's closure sugar in Rio ;) ?

To be fair, though I'm not sure to whom, I think someone promoted it  
before I did. ;-)

But the full details of my proposal included:

1. Binds early.
2. Binds strongly. (Weak closures are a separate implementation  
problem.)
3. Only generates a closure when not used at a call site though this  
should be purely an optimization.

The piece of syntax I will take credit for promoting since I don't  
think I'd seen it elsewhere before is:

	obj:[method](...)

and in this case:

	obj:[method]

Thereby allowing the method name to be an expression while at the same  
time not forcing the repetition of obj in an expansion of the colon  
operator.

I believe this is actually moderately easy to implement as a patch on  
the current Lua implementation. (I'd have to go find my notes on how  
to do so.)

Mark