On Fri, 18 Mar 2022 at 00:31, David Mertz, Ph.D. <david.me...@gmail.com> wrote:
>
> I just do this myself in my text editor (vim):
>
>
> But this is just cosmetic because I like to look at it this way. The actual
> file on disk contains `set()`, `<=`, `in`, `not in` and wouldn't be a problem
> for anyone without the same fonts installed, or require anyone to know odd
> key combos.
>
This is potentially confusing if you ever shadow the name 'set' (since
the word doesn't appear in the visual form, but does appear in the
source), but otherwise, it's a good solution.
Here's a crazy thought: What if we start by standardizing on {*()} as
an idiom, teach the optimizer to skip the tuple altogether, and then
encourage editors to (a) show it as an empty set glyph, and (b)
provide a convenient way to enter it? On disk, it would still be a
syntactic form that's compatible all the way back to Python 3.5 (I had
to check actually - the additional unpacking generalizations have been
around longer than I thought), but in the display, it would look quite
elegant.
Then, if it catches on, support for the actual ∅ symbol (btw, "⦰" is
actually "reversed empty set", but they're in the same category so
same diff) could be added as an alias for {*()}, at which point
editors could have an option to represent it either way.
For the record, here's the timings for the different forms:
rosuav@sikorsky:~$ python3 -m timeit -s 'from opcode import opmap as
o; f1 = lambda: set(); f2 = lambda: {*()}; f3 =
type(f2)(f2.__code__.replace(co_code=bytes([o["BUILD_SET"], 0,
o["RETURN_VALUE"], 0])), f2.__globals__)' 'f1()'
5000000 loops, best of 5: 78.6 nsec per loop
rosuav@sikorsky:~$ python3 -m timeit -s 'from opcode import opmap as
o; f1 = lambda: set(); f2 = lambda: {*()}; f3 =
type(f2)(f2.__code__.replace(co_code=bytes([o["BUILD_SET"], 0,
o["RETURN_VALUE"], 0])), f2.__globals__)' 'f2()'
5000000 loops, best of 5: 98.9 nsec per loop
rosuav@sikorsky:~$ python3 -m timeit -s 'from opcode import opmap as
o; f1 = lambda: set(); f2 = lambda: {*()}; f3 =
type(f2)(f2.__code__.replace(co_code=bytes([o["BUILD_SET"], 0,
o["RETURN_VALUE"], 0])), f2.__globals__)' 'f3()'
5000000 loops, best of 5: 62.8 nsec per loop
Sorry for the messy setup but I wanted something that would work on
multiple Python versions, so hardcoding a bytes literal wouldn't work.
I tried it on Python 3.8, 3.9, 3.10, and 3.11, and in each case, the
relative speeds (f2 slowest, f3 fastest) were maintained.
ChrisA
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