(Prolog) Hanoi

% Completed code from http://en.wikipedia.org/wiki/Prolog
PREDICATES
  hanoi(integer)
  move(integer,symbol,symbol,symbol)
  inform(symbol,symbol)
CLAUSES
  hanoi(N) :- move(N, left, right, centre).
  
  move(0, _, _, _) :- !.
  move(N, A, B, C) :-
    M = N-1,
    move(M, A, C, B),
    inform(A, B), 
    move(M, C, B, A).
  inform(X, Y) :-
    write("move a disc from the "),
    write(X),
    write(" pole to the "),
    write(Y),
    write(" pole"),
    nl.
  
  GOAL
    hanoi(4).