[Aldor-l] [Axiom-developer] Re: exports and constants

[Ralf Hemmecke]

> Of course. But if you want to print out things you must be
>> able to convert to something that you can put onto a screen.
> 
> Yes you are right. In Axiom such output is a matter resolved
> by providing (almost) every domain with a coercion function
> to the OutputForm domain. Since in Axiom lisp underlies
> everything, providing such a coercion is relatively easy.
> In Aldor as a stand alone high level language I am not sure
> exactly what the best solution is. Does it really make sense
> that such a high level language should care about the name
> that a particular programmer assigned to one of it's objects?

As I said before I don't aim at an implementation of reflections as a 
tool for the general user. I only want to have reflections for a few 
exceptional cases like AldorUnit or perhaps a debugger that is written 
in Aldor. Both would need a way to print the name of a function.
(In general, of course the name is irrelevant. That is why I don't want 
reflections.)

>>> MyDom: with
>>>   exports:Generator Category
>>>   add2:(MyDom,MyDom) -> MyDom
>>>   sub2:(MyDom,MyDom) -> MyDom
>>>   neg: MyDom -> MyDom
>>>  == add
>>>   import from Integer
>>>   Rep == Integer
>>>
>>>   exports:Generator Category == generate
>>>     yield with {add2:(MyDom,MyDom)->MyDom}
>>>     yield with {sub2:(MyDom,MyDom)->MyDom}
>>>     yield with {neg:MyDom->MyDom}
>>>
>>>   add2(x:%,y:%):% == per(rep(x) + rep(y))
>>>   sub2(x:%,y:%):% == per(rep(x) - rep(y))
>>>   neg(x:%):% == per(-rep(x))
>> I liked your code, but in fact that does not use reflection
>> at all and I think it should even compile. You are not doing
>> anything fancy.
> 
> Why do you say that this does not use reflection?

Because you give the "exports" constant explicitly. Suppose you later say

extend MyDom: with {foo:()->()} == add {foo(): () == {}}

Then exports$MyDom does not reflect the true exports since "foo" would 
be missing.

You don't relect about "MyDom" you just give an explicit constant.

> I agree that this is nothing "fancy". Actually, reflection is
> not really such a "fancy" concept at all, its just that we have
> got used to not having access to this sort of information in
> non lisp-based programming without first-order types.

Right, I am not used to reflection. Is there a collection of nice 
examples where reflection is a "must have"? I can only think about 
AldorUnit, a debugger and a way to ask a library which functionality it 
provides.

> Yes, I agree that this should compile now. Obviously Aldor
> does try to compile it but it fails for some obscure reason.

>> aldor -grun -laldor self2.as
> "self2.as", line 17:     yield with {add2:(MyDom,MyDom)->MyDom}
>                      ....^
> [L17 C5] #1 (Fatal Error) Compiler bug: no exit list for terrorSequence
> (ooops).
> 
> ------------
> 
> I guess this means I should submit a bug report ... but until
> Aldor is open source or we find some other way to deal with it
> I am not too strongly motivated.

I have the suspicion if you wrap the "with {..}" stuff with a Record, it 
might help. But it's a bug anyway.

 > Given the urgency (to us at
> least!) of resolving the issue of the open source status of
> Aldor, I am disappointed not to hear anything yet from Steven
> Watt or Mike Dewar as Mike did state directly in an email to
> me that they intended to discuss it during the recent meetings
> in Europe... :( I am again impatient and thinking about drastic
> alternatives.

I can assure you that Stephen and Mike discussed the issue when they 
where both in Dagstuhl. And Tim and me met Stephen in Sophia-Antipolis 
at the Bronstein conference. Stephen told me that he wants to sort out 
the license issue until the end of August. It would of course be best to 
have Aldor free before the beginning of the next semester.

Ralf