[Python-ideas] + operator on generators

[Sven R. Kunze]

Personally, I find syntactic sugar for concating interators would come 
in handy.

The purpose of iterators and generators is performance and efficiency.  
So, lowering the bar of using them is a good idea IMO. Also hoping back 
and forth a generator/iterator-based solution and a, say, 
list-based/materialized solution would become a lot easier.


On 25.06.2017 16:04, Stephan Houben wrote:
> I would like to add that for example numpy ndarrays are iterables, but
> they have an __add__ with completely different semantics, namely 
> element-wise ( numerical) addition.
>
> So this proposal would conflict with existing libraries with iterable 
> objects.

I don't see a conflict.

>
> Op 25 jun. 2017 2:51 p.m. schreef "Serhiy Storchaka" 
> <storchaka at gmail.com <mailto:storchaka at gmail.com>>:
>
>     It would be weird if the addition is only supported for instances
>     of the generator class, but not for other iterators. Why (n for n
>     in range(2)) + (n for n in range(2, 4)) works, but iter(range(2))
>     + iter(range(2, 4)) and iter([0, 1]) + iter((2, 3)) don't?
>     itertools.chain() supports arbitrary iterators. Therefore you will
>     need to implement the __add__ method for *all* iterators in the world.
>

I don't think it's necessary to start with *all* iterators in the world.

So, adding iterators and/or generators, should be possible without any 
problems. It's a start and could already help a lot if I have my 
use-cases correctly.

>     However itertools.chain() accepts not just *iterators*. It works
>     with *iterables*. Therefore you will need to implement the __add__
>     method also for all iterables in the world. But __add__ already is
>     implemented for list and tuple, and many other sequences, and your
>     definition conflicts with this.
>

As above, I don't see a conflict.


Regards,
Sven
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