Re: [Axiom-developer] Unions in Spad

[Gabriel Dos Reis]

Stephen Wilson <address@hidden> writes:

| *,
| 
| During my work figuring out the defintrf.spad bug, I noticed a
| shortcoming in the handling of unions.
| 
| Spad, internally, has two notions of Unions.  The first variety might
| be termed `regular', the other is, not surprisingly, termed `new'.
| 
| Regular Unions do not have tags associated with branches. For example:
| 
|       Union(Integer, String)
| 
| New Unions have tags, as in
| 
|       Union(int: Integer, str: String)

Both are documented in the Axiom book by Jensk and Sutor.

I believe, they are almost right.  Except one thing that I consider
a bug, not a feature:  the labels in unions and records should be
properly scoped/predicated instead of being dumped into the global space.

-- Gaby