From luke at stat.uiowa.edu  Tue Apr  1 12:32:15 2008
From: luke at stat.uiowa.edu (Luke Tierney)
Date: Tue, 1 Apr 2008 05:32:15 -0500 (CDT)
Subject: [Rd] callCC in 2.7.0
In-Reply-To: <16395614.post@talk.nabble.com>
References: <971536df0803300710t40f61256x78b9889a5c323924@mail.gmail.com>
	<16395614.post@talk.nabble.com>
Message-ID: <Pine.LNX.4.64.0804010528270.14754@nokomis.stat.uiowa.edu>

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.

Best,

luke

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



[Rd] callCC in 2.7.0
Luke Tierney