[Aldor-l] exports and constants

[Page, Bill]

On Wednesday, July 26, 2006 1:01 AM Christian Aistleitner wrote:
> ... 
> How does this fit together with
> 
> >> An attribute has no type.
> 
> (as cited by Bill from section 12.9 of the Axiom book)?
> Apparently, attributes have type "Category".
> 

In Aldor (AUG 7.9) the "with" clause has a slightly different
syntax than in the SPAD language of Axiom (to which the Axiom
book refers). Specifically in Aldor

  "L with { R }" is equivalent to "with { L ; R }"

and both L and R can be "category-valued expressions". In SPAD
only declarations, and attributes are allowed on the right hand
side. One is expected to write

  Join(L,R) with { ... }

if both L and R are categories - which is an equivalent syntax
in Aldor.

I suppose that in the original design of Axiom and SPAD it was
not obvious that attributes could be modelled as categories.
Or that the type system was a reasonable place in which to
implement axioms and logic. Historically Aldor was designed
to implement and improve on SPAD. It seems to me that one
design goal was to try to do "more with less". It that regard
I think Aldor does very well.

Regards,
Bill Page.