# [plt-scheme] Is there a set data-type?

On Fri, Feb 5, 2010 at 15:40, Laurent <laurent.orseau at gmail.com> wrote:
>* On Fri, Feb 5, 2010 at 15:12, Matthias Felleisen <matthias at ccs.neu.edu> wrote:
*>>*
*>>* On Feb 5, 2010, at 8:29 AM, Todd O'Bryan wrote:
*>>*
*>>>* What do people use for a set data-type? If there isn't one built-in,
*>>>* we're going to use a hash-table with #t as all the values.
*>>*
*>>* Just a tease: how would you use hashtable to represent infinite sets?
*>*
*>* From the top of my head, though that does probably not fit to the
*>* definition of an infinite set:
*>*
*>* (define towards-infinity-and-beyond (make-hash))
*>* (hash-set! towards-infinity-and-beyond 'zero '())
*>* (hash-set! 'me towards-infinity-and-beyond)
*
oops, please read on the last line:
(hash-set! towards-infinity-and-beyond) 'me towards-infinity-and-beyond)