[Rd] callCC in 2.7.0

Luke Tierney luke at stat.uiowa.edu
Tue Apr 1 12:32:15 CEST 2008

No.  First class continuations of the kind provided in scheme can be
used as a means to implement generators, but downward-only
continuations as currently provided in R are not sufficient for that.
This version is intended only as a non-local exit mechanism.



On Mon, 31 Mar 2008, f.jamitzky wrote:

> callcc is similar to the "yield" keyword in python and c#
> it lets you define e.g. a generator of lists of numbers.
> Gabor Grothendieck 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?
>> ______________________________________________
>> R-devel at 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:      luke at stat.uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu

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