mergeMap variations

[parloti]

I need three variations of the mergeMap operator as described below.

switchEqualMap(
    project /* Just like in mergeMap */,
    keySelector?: (outerValue: TValue) => TKey /* Like in distinct */,
    concurrent: number = Infinity /* Just like in mergeMap */
)

This operator would maintain a map of values obtained with keySelector and their respective internal active subscriptions. It would behave like the mergeMap, except if there is already an active subscription on the map for the value obtained with keySelector, in this case it should behave like the switchMap, canceling the active subscription and creating a new one.

---

exhaustEqualMap(
    project /* Just like in mergeMap */,
    keySelector?: (outerValue: TValue) => TKey /* Like in distinct */,
    concurrent: number = Infinity /* Just like in mergeMap */
)

Similar to switchEqualMap, but for repeated value of keySelector it should behave like exhaustMap instead of switchMap, maintaining the previous subscription and ignoring the current value.

---

concatEqualMap(
    project /* Just like in mergeMap */,
    keySelector ?: (outerValue: TValue) => TKey /* Like in distinct */,
    concurrent: number = Infinity /* Just like in mergeMap */
)

It is also similar to switchEqualMap, but to repeated value of keySelector it should behave like concatMap instead of switchMap, waiting for the conclusion of the previous subscription to process the current value.

---

I'm already testing my own implementation for rxjs 6, like this HigherOrderMapOperator. But I want to migrate to rxjs 7, and my code is no longer compatible.

I would also be happy with a combination of existing operators that is simpler than this Cancel repeated subscription in mergeMap.

Thanks in advance