At Mon, 5 Sep 2011 15:08:44 -0400, Danny Yoo wrote: > On Mon, Sep 5, 2011 at 2:18 PM, Shriram Krishnamurthi <s...@cs.brown.edu> > wrote: > > On Sat, Sep 3, 2011 at 11:17 PM, Shriram Krishnamurthi <s...@cs.brown.edu> > wrote: > >> Is there a way of checking whether a value position is undefined? > >> Specifically, I'm trying to recognize the undefined value put in > >> structures by SHARED. It appears that a undefined value is sometimes > >> EQ? to another one, but this doesn't seem to be specified in the > >> documentation (ie, that there is only one undefined value). > > > > Anyone have any thoughts on this? Is it okay to use EQ? > > According to: > > http://docs.racket-lang.org/reference/void.html > > we know the value of undefined is a constant, but there's no guarantee > that they're the same value.
The void and undefined constants are separate, but there really is only one of each at the `eq?' level. _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
