> Both of these are possible in C. See:
>
> https://stat.ethz.ch/pipermail/r-devel/2007-September/046943.html
Cool, thanks.
> It shows how to query an object to see if its a promise and but rather
> than extract the environment it shows how to copy a promise without
> evaluating it; however, it w
> Promises are an implementation detail -- we need to be able to change
> them, optimize them away, etc, so there is a limit on what we want to
> expose. Allowing a query of whether a binding is delayed or not
> should be OK but would want to think that through more carefully
> before committing t
