upmap(F, L) ->
    Parent = self(),
    Ref = make_ref(),
    [receive {Ref, Result} -> Result end
     || _ <- [spawn(fun() -> Parent ! {Ref, F(X)} end)
              || X <- L]].

safe_pmap_set_ok(F, S) ->
    case [R || R <- upmap(
                      fun (V) -> try F(V)
                                 catch Cl:Re -> {Cl, Re}
                                 end
                      end, sets:to_list(S)),
               R =/= ok] of
        []     -> ok;
        Errors -> {error, Errors}
    end.