this function becomes trivial if the default white/blacklist was expressed the same was as the config value;

load_filter_list(Key, Def) ->
  List = couch_config:get("couch_httpd_auth", Key, Def),
  re:split(Str, "\\s*,\\s*", [trim, {return, binary}]).

call it with load_filter_list("public_users_whitelist", "name"), etc.