On Sun, 30 Mar 2008, Gabor Grothendieck wrote: > I think the only relationship to that is the name since > it does not appear to allow one to leave a function > in the middle of its processing and re-enter it back > at that point -- which is what would be needed.
The article conflates basic CPS with having first class continuations as in Scheme. The discussion about compilers and tail calls only requires downward-only continuations of the kind provided by R's current callCC. The user interface and coroutine discussion requires continuations that can be run outside of their creating context. The most sophisticated variant, as provided in Scheme, also allows continuations to be run more than once. I don't think any of the examples in the Wikipedia article need that, but there is some interesting work on using that to model web browsing behavior. At any rate, there is plenty of precedent for using callCC as the name for the construct here even when the continuation is no longer valid outside of the creating callCC call. So the relationship is more than just the name. luke > > On Sun, Mar 30, 2008 at 12:04 PM, <[EMAIL PROTECTED]> wrote: >> >>> Would anyone like to explain if callCC in R 2.7.0 gives >>> anything that on.exit does not already provide? >>> >>> It seems that the exit condition once defined cannot >>> be added to overridden whereas with on.exit multiple >>> on.exit's add additional on.exits rather than being ignored. >>> >>> Is this important? >> >> It facilitates a completely different style of programming - see >> http://en.wikipedia.org/wiki/Continuation-passing_style >> >> -- >> http://had.co.nz/ >> > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > -- Luke Tierney Chair, Statistics and Actuarial Science Ralph E. Wareham Professor of Mathematical Sciences University of Iowa Phone: 319-335-3386 Department of Statistics and Fax: 319-335-3017 Actuarial Science 241 Schaeffer Hall email: [EMAIL PROTECTED] Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
