Problems with Strings

[Pablo Dejuan]

Hi. I'm new in this and I have dificulties using strings. I tried to do 
an "inverese" function that should turn "bac" into "cab" but instead of 
this I get [98,[97,[99,[]]]] which I noticed that are tha Ascii codes 
for c, a, and b.

Here is the code:
inversa("") -> "";
inversa([Ini|Cont]) -> Inv= inversa(Cont), [Ini,Inv].

Thanks In Advance.