#10963: More functorial constructions
-------------------------------------+-------------------------------------
Reporter: nthiery | Owner: stumpc5
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.1
Component: categories | Resolution:
Keywords: days54 | Merged in:
Authors: Nicolas M. Thiéry | Reviewers: Simon King, Frédéric
Report Upstream: N/A | Chapoton
Branch: | Work issues:
public/ticket/10963 | Commit:
Dependencies: #11224, #8327, | 8045aa4a4b7ada735b3eb6055382f9b341a39f1e
#10193, #12895, #14516, #14722, | Stopgaps:
#13589, #14471, #15069, #15094, |
#11688, #13394, #15150, #15506 |
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Comment (by nthiery):
Given the number of questions poping out recently, I decided this
morning that I might as well write the developer's documentation for
axioms instead of spreading the information in comments on this track
ticket. Beware: so much more work for you to review :-)
I hope it will be convincing about the design decisions and, up to
some point, the implementation. It will take me some more time (until
tomorrow evening maybe?), so don't start hacking around in the mean
time!
I can answer right now to Nils last comment though. I believe that
{{{
C.FiniteDimensional()
}}}
is *really* better than
{{{
C.with_axiom("FiniteDimensional")
}}}
Rationale:
- This idiom is short, unambiguous and super expressive. Look at the
non trivial examples in the primer and see how painful those would
be with the _with_axiom idiom. It is backed up by three years of
practical usage, and during that period it has appeared, as far as I
know, totally natural to all those who played with it.
- It's nice w.r.t. introspection:
- The axioms of C appear in the tab completion of C. In particular
you get an easy access to the list of them.
- introspection on C.FiniteDimensional gives specific documentation
on what each axiom is about.
- It's consistent with what we have been using for years for
functorial constructions (Cartesian products, Graded, ...)
- Categories have few operations. So the odds of a name clash is low.
- You can *also* use C._with_axiom(...) if you feel inclined to, for
example if the name of the axiom you are interested in is stored in
a variable. I am happy to rename C._with_axiom to C.with_axiom if
you believe it deserves to be public.
- This idiom does not depend on the actual implementation behind the
scene. We could still decide later on to store the links in a
database or whatever.
Cheers,
Nicolas
--
Ticket URL: <http://trac.sagemath.org/ticket/10963#comment:367>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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