I don’t see anything Object Oriented in your question. It seems you want mutable data structures. Immutability is expected throughout BEAM code.

IMO the person.put syntax is deceiving, it can’t really “mutate” the thing it looks like it should. For instance (hypothetical, won’t compile):

person = %{region: "east-1"}
also_person = person
person.put(:region, "west-1")

# what is also_person.region?

person and also_person start out referring to the same Map, but then person is changed to refer to a different, updated Map. An OO-style mutation would result in also_person.region changing as well.

You could get close as-is with pipes and import:

import Map

person =
  person
  |> put(:region, "west-1")

or even (with the two-argument form of put_in):

person = put_in person[:region], "west-1"

The pipe syntax tends to lead to a lot of the “de-sugared Python” flavor, since it threads through the first argument.

Also worth reading the old discussions around “tuple calls” (Tuple Calls) which covers some similar conceptual space.

Mutation

person.put(:region, "west-1")

vs. new value

person = Map.put(person, :region, "west-1")

at least in my mind.