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[Python-Dev] Every Release Can Be a Mini "Python 4000", Within Reason (was (name := expression) doesn't fit the narrative of PEP 20)


FWIW, this thread is about what "Python 4000" means and does not mean.
Namely, Python feature deprecation and removal is not prohibited but
the bar is high (as always), especially for syntax.  While I
appreciate the level of interest in certain under-consideration
proposals, you'd be better served by continuing discussion about that
proposal in other threads.  Thanks!

-eric

On Mon, Apr 30, 2018 at 7:25 PM, Terry Reedy <tjreedy at udel.edu> wrote:
> On 4/30/2018 4:00 PM, Jeff Allen wrote:
>
>> They were not "statements", but "formulas" while '=' was assignment (sec
>> 8) *and* comparison (sec 10B). So conversely to our worry, they actually
>> wanted users to think of assignment initially as a mathematical formula
>> (page 2) in order to exploit the similarity to a familiar concept, albeit
>> a=a+i makes no sense from this perspective.
>
>
> When explaining iterative algorithms, such as Newton's method,
> mathematicians write things like a' = a+1 or a(sub i+1 or sub new) = f(a(sub
> i or sub old)) .  For computer, we drop the super/subscript.  Or one can
> write more circuitously,
> anew = update(aold)
> aold = anew
> The abbreviations should be explained when teaching loops.
>
> For proving that the body of a loop maintains a loop constant, one may
> reinstate the super- or sub-script.
>
> --
> Terry Jan Reedy
>
>
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