[Aldor-l] Should this "parser" work?

[Martin Rubey]

Dear Christian,

thank's for your comments. I think I understand now. So here is the same setup,
rewritten. I omitted A, because it should make no difference. In fact, I
checked, replacing 

        A: CC == Atom;
        res: List CC := [A for x in p];        

with

        res: List CC := [];
        for x in p repeat
          res := cons(Atom, res);

gives the same result. Curiously, the compiler doesn't compile

        res: List CC := [Atom for x in p];

-------------------------------------------------------------------------------

mem loc   depends on            Name / Variable   comment

00001000:                       CC

00002000: 00001000              List CC

00003000:                       Atom

00005000: 00003000 00000000     res               contents pointer

00006000:                                         result of E(1)

Now, the question is what E(1) really is. In the setup as written above one
would think it depends only on 00003000, which wouldn't be the "good" result.

The other possibility is

> Union(Atom, Cross( apply( 00005000, 1 ), apply( 00005000, 1 ) ) ) due to lazy
> evaluation. This would explain why the whole thing works, bit is very, very
> tricky.

However, it just occurred to me that maybe the setup is rather

mem loc   depends on            Name / Variable   comment

00001000:                       CC

00002000: 00001000              List CC

00003000:                       Atom

00003001:                                         an instance of Atom

00005000: 00003001 00000000     res               contents pointer

00006000:                                         result of E(1)

which would explain what happens. 


Do I understand correctly: "Universe" is the collection of [identifier, type]
in scope at a given point of execution?

Martin