On Tue, Aug 26, 2014 at 3:12 PM, John Cremona <[email protected]> wrote:
> Sounds like a reasonable plan if you (or someone) can be bothered to
> sort out the chenges which will need to be made in code and doctests!
Even then, personally I don't like it. See below for a different
suggestion that is less intrusive.
> There will be places where we now have: for p in primes(10^8):
> do_something_with(p) which will still work when primes() returns a
> list, so will not result in doctest failures, but which should be
> changed. This will be rather tedious.
>
> On the plus side, I make the point that all these are functions at the
> top level which will be discovered by beginners for whom
>
> sage: primes(100)
> <generator object primes at 0x7f9335465a50>
>
> will just confuse. Experts can know about and use the iterator forms
> of the functions.
We could certainly make it do this with little effort:
sage: P = primes(100); P
Prime numbers of less than 100
We could then have
for x in P:
...
be the usual iterator. One could also do:
sage: P.list()
[...]
to get back a list. And one could do
sage: len(P)
to get the number of primes, without computing them. So... my
counterproposal is to make primes return a cython class with a few
methods. This breaks new code, and will be more new user friendly.
>
> John
>
> On 26 August 2014 14:00, Vincent Delecroix <[email protected]> wrote:
>> Hello,
>>
>> Right now, we have the following functions
>> - primes: an iterator over primes
>> - prime_range: a list of primes (in Cython)
>> - prime_powers: a list of prime powers
>> - prime_power_range: another function that return a list of prime
>> powers (in Cython from #16880)
>>
>> Given that
>> - we can implement iterator in Cyhon
>> - most function that end with 's' return lists (elliptic_curves,
>> prime_divisors, quadratic_residues, ...)
>>
>> What do you think about:
>> - move everything in Cython in `fast_arith.pyx`
>> - having `primes` and `prime_powers` return lists
>> - having `prime_iterator`and `prime_power_iterator` return iterators
>> (with deprecation and everything)
>>
>> Best,
>> Vincent
>>
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--
William Stein
Professor of Mathematics
University of Washington
http://wstein.org
[email protected]
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