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Re: [Axiom-developer] Re: fixing SPAD

From: Waldek Hebisch
Subject: Re: [Axiom-developer] Re: fixing SPAD
Date: Sat, 19 May 2007 18:46:10 +0200 (CEST)

Gabriel Dos Reis wrote:
> On Sat, 19 May 2007, Martin Rubey wrote:
> | Are you saying:
> | 
> |   if A and B or C then ...
> | 
> | should be, but currently isn't allowed in the context of conditional 
> exports?
> | (I think it is allowed already now.)
> I'm saying that we seriously consider the above when A, B or C
> happen to be patterns (`is form') or attribute queries (`has form').
> Note that from Spad point of view, they are just predicates.

>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.  I agree that also complicated expressions should be
allowed, but support (or lack of it) does not cause conceptual or
practical difficulties: complicated expressions are just syntatic
sugar for combinations of simple expressions.

                              Waldek Hebisch

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