[junke]

"update", "put" are already available in Erlang[0] and work with nested records[1] if I understand correctly. Likewise, it seems that LFE has map-update for the same use cases[2].

[0] http://erlang.org/doc/man/maps.html

[1] http://erlang.org/doc/reference_manual/records.html#id86378

[2] https://github.com/rvirding/lfe/blob/develop/doc/user_guide....