Interest in a compactScan operator ?

[twittemb]

Hi everyone,

lately I faced a use case where a reducer function that I pass to a “scan” operator could return an optional.

the expected behaviour was: if the function returns nil then there is no change made in the accumulator and the scan operator continues with the next values.

the signature would be something like:

compactScan(initial: A, _ nextPartialResult: (A, Output) -> A?) -> AnyPublisher<A, Failure>

What do you think?

[twittemb]

Hey @freak4pc do you think it would be valuable ?

Thanks.

[freak4pc]

That sounds like a fun and useful operator, I would be up for accepting a PR for it :) Thanks!

[twittemb]

Hey @freak4pc

I've made the PR -> #100

Let me know what you think.

Thanks.

[freak4pc]

I kinda like the idea. Anyone has additional opinions about it? @CombineCommunity/contributors

[oconnelltoby]

I think a better signature could be:

scan(into: A, _ nextPartialResult: (inout A, Output) -> Void) -> AnyPublisher<A, Failure>

This would allow the user to achieve the same thing by simply not calling nextPartialResult when not needed rather than returning nil.