title: What is the need for immutable/persistent data structures in erlang
body: <p>Each Erlang process maintains its own private address space. All communication happens via copying without sharing <em>(except big binaries)</em>. If each process is processing one message at a time with no concurrent access over its objects, I don't see why do we need immutable/<a href="https://en.wikipedia.org/wiki/Persistent_data_structure" rel="nofollow noreferrer">persistent data structures</a>.</p>