Re: RFC 104 (v1) Backtracking

[Jeremy Howard]

Johan Vromans wrote:
> Damian Conway <[EMAIL PROTECTED]> writes:
>
> >    > As I understand things:
> >    >
> >    > BLOCK1 andthen BLOCK2
> >    >
> >    > evaluates BLOCK1 and then if BLOCK1 evaluates to "true" evaluates
> >    > BLOCK2.  If BLOCK2 evaluates to "true" we're done.  If BLOCK2
> >    > evaluates to "false", then BLOCK1 is re-evaluated.
> >
> > So how is that different from:
> >
> > do BLOCK1 until do BLOCK2
>
> It's the same.
> But the real fun starts when blocks and functions can suspend and
> resume.
>
There's already an RFC for coroutines that proposes allowing suspension and
resumption of subroutines. Do the proposed backtracking operators buy
anything that do/until/coroutines don't provide?