Erlang: maps:merge(M1,M2). Composable & preserving. Variadic doesn't matter much as can do fold over a sequence of maps: lists:foldl(fun(E,A) -> map

Erlang: maps:merge(M1,M2). Composable & preserving. Variadic doesn't matter much as can do fold over a sequence of maps: lists:foldl(fun(E,A) -> maps:merge(E,A) end, #{}, [M1,M2,M3, ...]).