Re: [Rd] Capturing environment associated with a promise

From: <>
Date: Mon, 08 Oct 2012 09:35:52 -0500

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 to this.


On Mon, 8 Oct 2012, Hadley Wickham wrote:

> Hi all,
> It's possible to capture the expression associated with a promise
> (using substitute). Is there any way to capture the environment
> associated with a promise? Similarly, is there any way to tell if
> something is a promise without accidentally evaluating it?
> Thanks!
> Hadley

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:
Iowa City, IA 52242                 WWW:

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