On Thu, Apr 2, 2009 at 2:19 PM, Gabriel Dos Reis <g...@cs.tamu.edu> wrote:
> Bill Page writes:
>
> | Since BinarySearchTree is a particular class of BinaryTree for
> | consistency in BinarySearchTree I would expect to see:
> |
> | Implementation == BinaryTree(S) add
> | Rep == List Tree S
>
> As I said, I would not. I would not expect any definition of Rep
> at all. The domain extension says BinaryTree(S) is the Rep of
> BinarySearchTree(S).
>
Sorry, then this is my confusion. As I said, I expected that the Rep
of BinarySearchTree should be the same as the Rep of the domain from
which it inherits - *not* the domain itself.
My (perhaps poor) understanding of add-inheritance
NewDomain(): with
... exports ...
== OldDomain add
... body ...
was that all functions and constants defined in the OldDomain
(regardless of whether they are exported or not) are visible to code
in the body of the new domain. Is that true or not?
In the Axiom Book it says:
13.8 Add Domain
...
The Implementation part of a definition can optionally specify an “add-
domain” to the left of an add (for QuadraticForm, defines SquareMatrix(n,K)
is the add-domain). The meaning of an add-domain is simply this: if the cap-
sule part of the Implementation does not supply a function for an operation,
Axiom goes to the add-domain to find the function.
---
Perhaps it is not so clear what "Axiom goes to the add-domain to find
the function" means.
In clifford.spad.pamphlet I see:
SM ==> SquareMatrix
...
Impl ==> SM(n,K) add
Rep := SM(n,K)
which obviously corresponds to your interpretation, Gaby. There are
numerous other examples of this in the library.
But in 'xlpoly.spad.pamphlet' I see:
LiePolynomial(VarSet:OrderedSet, R:CommutativeRing) : Public == Private where
...
Private == FreeModule1(R, LWORD) add
import(TERM)
--representation
Rep := List TERM
and in 'xpoly.spad.pamphlet' we have:
FreeModule1(R:Ring,S:OrderedSet): FMcat == FMdef where
...
FMdef == FreeModule(R,S) add
-- representation
Rep := List TERM
and in 'poly.spad.pamphlet':
FreeModule(R:Ring,S:OrderedSet):
Join(BiModule(R,R),IndexedDirectProductCategory(R,S)) with
if R has CommutativeRing then Module(R)
== IndexedDirectProductAbelianGroup(R,S) add
--representations
Term:= Record(k:S,c:R)
Rep:= List Term
...
which looks more like what I expected to find.
> | Note: The 2nd line above is not required in OpenAxiom.
>
> And I think that is a coherent, simple notation for a simple semantics.
>
If were true that functions local to OldDomain are available in
NewDomain and if the Rep in NewDomain is just OldDomain then I would
be worried about how to correctly call these functions.
Regards,
Bill Page.
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