#14608: Symbolic functions break the __hash__ contract
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Reporter: vbraun | Owner: burcin
Type: defect | Status: new
Priority: major | Milestone: sage-6.4
Component: symbolics | Resolution:
Keywords: | Merged in:
Authors: | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
Dependencies: | Stopgaps:
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Comment (by nbruin):
Now that we've decided to sacrifice readability for reducing the chance of
name collisions with variables in conversion from SR to maxima:
{{{
sage: x._maxima_()
_SAGE_VAR_x
}}}
we could ensure that name translation from SR to maxima is injective as
well. Theoretically, we could have
{{{
sage: function('f')._maxima_()
_SAGE_FUNC_NAME_f
sage: function('f',nargs=1)._maxima_()
_SAGE_FUNC_NARGS_1_NAME_f
}}}
or something similar. Since LISP uses interned strings for symbols, it
wouldn't even be inefficient in the "enhanced" interface to maxima_lib:
once the dictionaries are seeded, the strings wouldn't be parsed. The
strings-based interface would of course have a bit of a penalty, because
it does all kind of regex stuff, so string length actually affects
performance (but you'd probably have to work very hard to notice it)
Note that this issue came up again on
[http://ask.sagemath.org/question/30590/substituting-derivatives-in-
taylor-expansions/ ask sagemath].
--
Ticket URL: <http://trac.sagemath.org/ticket/14608#comment:9>
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