Thanks everyone, for the answers. I didn't knew the *elem* function. That will make my life easier. For the sake of simplicity, I changed the code to a shorter *userRegistration* function, eliminating the *checkUser* function: userRegistration user list

| elem user list = list | otherwise = user:list

It did worked fine. I'm glad that I can count with this list in my learning process. Thanks again. -- ____________________________________________________________________________ Francisco Borges "Chicão" Junior .......................................................................................... http://pedepinico.blogspot.com .......................................................................................... "Quem de boa vontade carrega o difícil, também carrega o menos difícil..." Lao Tsé - Tao Te Ching