Associative arrays with void values

[Michel Fortin]

On 2009-04-13 01:53:41 -0400, bearophile <bearophileHUGS at lycos.com> said:

>> (Incidentally, I also think the natural set operations, like
>> intersection and mutual exclusion, are just as handy for maps as for sets.)
> 
> It's less semantically clean to define certain set operations on AAs, 
> because for example you have to decide what to do when keys are equal 
> but their values are not.

You could pass an alias to a function that would perform the merge 
between values. That way, there's not ambiguity.


> You can avoid such semantic troubles altogether performing set 
> operations just only on the lazy view of the keys.

That'd require two passes: one for the keys, a second for getting the 
values from both sides (merging the values). It's going to be less 
efficient.

-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/