Support of algebraic operations on sets

Bert Freudenberg bert at freudenbergs.de
Fri Jun 15 17:33:42 UTC 2007

```On Jun 15, 2007, at 19:23 , sig wrote:

> On 15/06/07, Bert Freudenberg <bert at freudenbergs.de> wrote:
>> On Jun 15, 2007, at 18:58 , sig wrote:
>>
>> > Lets take an example from real life: we have two dictionaries with
>> > translation of words from one language into another.
>>
>> book1 := {'hi'->'ho'. 'mu'->'ma'} as: Dictionary.
>> book2 := {'hi'->'ho'. 'foo'->'bar'. 'be'-> 'boo'} as: Dictionary.
>>
>> > Now, the task is
>> > to compare these books to find out, what book contains more
>> > translations
>>
>> book1 size > book2 size
>>
>> > and to find out what words is missing in first book that
>> > holds second one.
>>
>> new := book2 keys difference: book1 keys
>>
>> > Then, after finding them out, merge new words with
>> > first book.
>>
>> new do: [:k | book1 at: k put: (book2 at: k)].
>
>  book1 union: book2

>>
>> > Or remove them from second book.
>>
>> new do: [:k | book2 removeKey: k].
>>
>  book2 difference: (book1 intersection: book2)
>
>
> can't you see the difference?

Sure. As I said before, you seem to think of Dictionaries as
Collections of Associations. So just use a Collection of Associations:

| book1 book2 new |
book1 := {'hi'->'ho'. 'mu'->'ma'}.
book2 := {'hi'->'ho'. 'foo'->'bar'. 'be'-> 'boo'}.
book1 union: book2.
book2 intersection: book1.

But for *Dictionaries* these semantics would be nonsensical.

- Bert -

```