将String转换为用户定义的类型。输入输出问题

Hello: I have a function which gets a string, and regarding what it gets, it calls some other functions. All but one of them, do not needs arguments. But the one that do needs it expect to receive an argument which type is defined by me. My intention is to require input to pass. But, using getLine, getChar, getInt, store the input keeping the type ([Char],Char,etc), and I need to pass rough input to that function so the inferring system is able to detect that its type is my user-defined type (Fecha).Hello: I have a function which gets a string, a