David,
  Try using an IdentityDictionary instead of a Dictionary.
Phil

David Farber wrote:

> today's puzzle is:
>
>     Dictionary new
>         at: (Set with: 1) put: 'is';
>         at: (Set new add: 1; yourself) ifAbsent: ['isnot']
>
> why does this little snippet *sometimes* answer 'is' and *sometimes* answers
> 'isnot'?
>
> i ask because i am trying to use Sets as keys in a Dictionary, but i am
> getting the non-deterministic behaviour witnessed above.
>
> help, commments, suggestions greatly appreciated.
>
> dave
>
> --
>         j. david farber
>     oo architect+mentor
> numenor labs incorporated
> in sunny boulder colorado
>     dfarber at numenor.com
>         www.numenor.com