> I recall that during the Aldor/Axiom workshop Stephen Watt suggested > that there might be some cases when it would be interesting to define > a "singleton" category which specifically satisfies a given domain. > Suppose there was an operation which evaluates to a category 'Cat(D)' > - sort of like Join except it takes a domain D as parameter. By > definition we would have > > D has Cat(D) > True > > for all domains D. Now we could easily define a new domain that > "extends" D by writing: > > )abbrev domain NEWD NewD > NewD():Cat(D) with ... > == D add > ...
That is (of course) not completely like "extend" since it defines a *new* domain NewD instead of extending D. And if you just have CatD instead of Cat(D), you can achieve the same thing. Parametrization would only make sense to me if that definition of NewD appears inside the "add" of a constructor Foo that has D as a parameter. But in that case the category of D (that is actually useful) is known from the definition of Foo. So what did you have in mind with the above? > But more interesting perhaps is that we could also easily write a > package that adds virtual functionality to D (and any domain that > extends D) without defining a new domain: > > )abbrev package EXTD1 ExtD1 > ExtD1(D1:Cat(D)): with > foo: D1 -> D1 > ... > == add > ... > > Remember the only the domain D or any domain that "extends" D satisfies > Cat(D). I don't see why one cannot do this with CatD instead of Cat(D). Ralf --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/fricas-devel?hl=en -~----------~----~----~----~------~----~------~--~---
