Re: [Axiom-developer] Re: fixing SPAD

[Ralf Hemmecke]

> > From aggcat.spad.pamphlet:
>
>    if Entry has SetCategory and % has finiteAggregate then
>       entry?: (Entry,%) -> Boolean
>         ++ entry?(x,u) tests if x equals \axiom{u . i} for some index i.
>
> Form aggcat2.spad.pamphlet:
>
>       if B has ListAggregate(R) or not(B has shallowlyMutable) then
>         -- A is a list-oid, and B is either list-oids or not mutable
>         map(f, l) == construct [f s for s in entries l]
>
> So, as Martin wrote simple boolean operators already work.  I belive
> that there are restrictions, namely that more complicated expressions
> do not work.

Martin, correct me if I am wrong...  But I guess Martin meant that 
something like

define ResidueClassRing(R: CommutativeRing, p: R): Category == with {
    Ring;
    if prime? p then Field;
    ...
}

which would be perfectly fine in Aldor does not work in SPAD.

In contrast to "has", "is", "and", etc. the function "prime?" is not 
defined by the language and thus cannot be evaluated at compile time.
In Aldor that is delayed until the time that category is first used (at 
runtime). Only then the actual exports are computed.

Ralf