[Python-ideas] Reuse "for" to express "given"

Alexander Belopolsky alexander.belopolsky at gmail.com
Thu May 24 17:47:59 EDT 2018


On Thu, May 24, 2018 at 4:59 PM Matt Arcidy <marcidy at gmail.com> wrote:

>
>
> On Thu, May 24, 2018, 11:47 Alexander Belopolsky <
> alexander.belopolsky at gmail.com> wrote:
>
>> > But I do have a mathematics background, and I don't remember ever
>> seeing
>> > "for x = value" used in the sense you mean.
>>
>> That's so because in mathematics, "for" is spelled ":" as in
>>
>>  {2*a* : *a*∈*Z*}
>>
>> If you can read the above, you should not have trouble reading
>>
>>  {2*a* + *b* : *a*∈*Z *: *b = *1}
>>
>
> Inverted "A" is "for all", and colon means "such that".  It may be
> acceptable somewhere to use a colon as you do,
>

See <https://en.wikipedia.org/wiki/Set_notation>.  Also, "[list
comprehensions] is Python's way of implementing a well-known notation for
sets as used by mathematicians." <
https://www.python-course.eu/list_comprehension.php>.  Although, the latter
uses "|" instead of ":".
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