Support of algebraic operations on sets

Gary Chambers gazzaguru2 at
Fri Jun 15 13:58:06 UTC 2007

I would expect difference, in this case, to have the common element taken
from "a" rather then "b", seeing as #difference: is non-commutative.

-----Original Message-----
From: squeak-dev-bounces at
[mailto:squeak-dev-bounces at] On Behalf Of Bert
Sent: 15 June 2007 2:51 pm
To: The general-purpose Squeak developers list
Subject: Re: Support of algebraic operations on sets

On Jun 15, 2007, at 14:45 , sig wrote:

> actually i missing these operations for dictionaries.
> in current implementation if you diff/union on two dictionaries, 
> you'll find out that associations play role as set elements, not keys.
> for dictionaries 'a difference: b' i get not exactly what i would
> expect.

Dictionaries are like other collections - a collection of  
"elements" (the values). The keys are only interesting for accessing  
- like indices on Arrays.  #do: operates on the values. So does  
#select:, and #difference:. You wouldn't expect #difference: on an  
Array to work on its indices, would you?

- Bert -

More information about the Squeak-dev mailing list