[Python-Dev] Retrieve an arbitrary element from a set without removing it (original) (raw)
Terry Reedy tjreedy at udel.edu
Sat Oct 24 21:37:13 CEST 2009
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Guido van Rossum wrote:
On Sat, Oct 24, 2009 at 10:34 AM, Alexander Belopolsky <alexander.belopolsky at gmail.com> wrote:
To me, however, a set seems to be a container that is a specialization of a dict with values and keys being the same. That's absurd; the mapping provides nothing useful.
Given Alexander's premise, I agree with your response. But his premise is wrong. Python's current builtin set class maps abstract equivalence classes to representative members. And this is useful. Mapping arbitrary members of such classes to representative members, sometimes called 'canonical', is a standard problem/goal in math. String interning is an application of this idea.
Terry Jan Reedy
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