RxScala mergeMap and concatMap bindings missing

[headinthebox]

Bindings for mergeMap and concatMap are missing in RxScala.

My proposal is to merge mergeMap and flatMap.

[benjchristensen]

@zsxwing Can you get these in soon before 0.19? Otherwise we can pick them up in 0.19.1.

By the way, mergeMap was created as an alias after discussion with you when we created concatMap and switchMap. The idea was to have "map" functions for each of merge, concat, and switch, but that flatMap is the term everyone uses for mergeMap so both would exist.

It seems you feel differently now? Should we deprecate mergeMap in rxjava-core and remove it when we hit 1.0RC?

[headinthebox]

Totally inconsistent I know, but I like to have all the aliases in RxJava core, but for the Scala bindings it feels more natural to only have flatMap and drop the mergeMap alias. But as I say, this is totally irrational ;-) and I would be OK to have all.

[zsxwing]

@zsxwing Can you get these in soon before 0.19? Otherwise we can pick them up in 0.19.1.

@benjchristensen this one will not be a breaking change in RxScala. So both are good to me.

[headinthebox]

@zsxwing Any preference? We can always add mergeMap later, but once we put it in as an alias for flatMap it is in forever.

[jbripley]

Speaking as a user of RxScala and Scala, I would say just to have flatMap, since that's what a Scala user would expect. Anything inherit in the missing mergeMap functions that would make that confusing?

[zsxwing]

@headinthebox I mean now there is only a flatMap method in RxScala, so we can add other methods to RxScala at any time without breaking anything. Never mind. Already sent a PR to add them, #1304