[PROLOG] How to insert an element in list?

%program to insert an element in list



domains

 A=symbol *.

predicates

 addsym(A,symbol,integer,A).

clauses

 addsym([],S,N,Q):-

  N<>0.

 addsym(P,S,N,[S|Q]):-

  N=0,!,

  addsym(P,S,-1,Q),

  write("inserted").

 

 addsym([H|T],S,N,[H|Q]):-

  B=N-1,

  addsym(T,S,B,Q),

  write("ins").