Currently it appears impossible to use `eachWhere` with a map. It is formally possible to invoke `eachWhere` on a `Map[A, B]`, but it would result in this method using `Iterable[(A, B)]` as the output for setting the value, which causes type mismatch errors. My use case is as follows. I have a map like `Map[String, SomeValue]` and I need to modify only those entries whose key satisfies some predicate: ```scala val predicate: ((String, SomeValue)) => Boolean = { case (k, _) => someConditionOnKey(k) } modify(_.sources.eachWhere(predicate).nested.value) ``` Apparently there is no simple way to do it now. Having an ability to use `eachWhere` on a map would solve the issue.