Inclusive takeWhile

[OliverJAsh]

Hi!

Do you have any plans to add an inclusive takeWhile?

An example of where this would be useful:

[1,2,3,4].takeWhile(x => x < 3)
// [ 1, 2 ]
[1,2,3,4].takeWhileInclusive(x => x < 3)
// [ 1, 2, 3 ]

Note, although it is easy to change the function in this example to achieve the same result, in my use case I do not want to execute next on the value after the last desired output.

[marcinnajder]

Hi!

Thanks for question :) I don't have any plan to add such a operator. It's because I didn't see any use case for it (but I see it can be useful). My background is .net (also Rx and Ix) and there is only takeWhile, here is the whole list of operators https://github.com/marcinnajder/powerseq/blob/master/docs/mapping.md.

But you can always add a new operatator seamlessly to powerseq without modifying source code of powerseq. Just copy a file https://github.com/marcinnajder/powerseq/blob/master/src/operators/takewhile.ts to your project, change it to takeWhileInclusive and import it from ES6/TS file. Everything should work fine. We can also consider adding it to powerseq.

Have you seen takeWhileInclusive operator in any other technology/language?

[OliverJAsh]

There is precedent for this in RxJava, where takeUntil takes a function and is inclusive:

http://reactivex.io/RxJava/javadoc/rx/Observable.html#takeUntil(rx.functions.Func1)

I see there is also discussion about adding this to RxJS ReactiveX/rxjs#2420