Re: [Axiom-developer] Unions in Spad

[Ralf Hemmecke]

> However, there is another problem: the signature of the index map
>      g: I->List SetCategory
> has syntax problem. (So, alas, all my examples inherit this problem.) A list 
> (more
> correctly, a set) of domains in the SetCategory is NOT a domain and hence 
> cannot be used as
> the target of a map. So we have to turn a list or set into a domain, much 
> like turning a
> list of tags into a domain (TagsAsDomain).  Here however, we are one level 
> higher because
> we are trying to make a set of *domains* such as {Integer, String} into a 
> domain.
> 
> While there is probably a way to do this in Lisp, the question is how should 
> a user of
> Axiom input this map g? It looks like we need to capture this at the algebra 
> level and make
> all these maps into a domain, too. So domains and perhaps even categories 
> must be first
> class objects. Unfortunately, even the domain Any does not capture sets of 
> domains as
> objects.  This despite the Rep for Any is Record(dm:SExpression, ob:None). 
> The Interpreter
> refuses to convert domains into objects of Any.
> 
> -> (1) k:List Any:= [Integer, String]
> 
>     Cannot convert an element of the construct to type Any.

Interesting. Now you also stumble over the same problem.

http://www.aldor.org/pipermail/aldor-l/2007-June/000640.html

Ralf