Mingle n lists by successively taking elements of each list. The lists don't need to be of the same size.

mingle_lists.erl

%% Mingle n lists by successively taking elements of each list. The lists don't need to be of the same size.
%% @spec mingle(ListOfLists::[List::[term()]]) -> Result::[term()] 
mingle(ListOfLists) ->
    mingle(ListOfLists, []).
mingle([], Result) ->
    lists:reverse(Result);
mingle(ListOfLists, Result) ->
    {NewListOfLists, NewResult} =
        lists:foldl(fun(List, {ListOfListsAcc, ResultAcc}) ->
                            case List of
                                [] -> {ListOfListsAcc, ResultAcc};
                                [Head|Rest] -> {[Rest|ListOfListsAcc], [Head|ResultAcc]}
                            end
                    end,
                    {[], Result},
                    ListOfLists),
    
    % must reverse to preserve the ordering of the list of lists
    mingle(lists:reverse(NewListOfLists), NewResult).