gistfile1.hrl

group_by2(F, [H|T]) ->
    group_by2(F, T, [H], []).

group_by2(_, [], [], Acc) ->
    lists:reverse(Acc);

group_by2(F, [], Buf, Acc) ->
    group_by2(F, [], [], [Buf|Acc]);

group_by2(F, [H|T], [HBuf|_TBuf] = Buf, Acc) ->
    case F(H, HBuf) of
        true -> group_by2(F, T, [H|Buf], Acc);
        false -> group_by2(F, T, [H], [lists:reverse(Buf)|Acc])
    end.