I'm doing an Prolog exercise that tries to decode a list.
decodifica([],[]).
decodifica([rlec(X,1)|L1],[X|L2]).
decodifica(L1,L2).
decodifica([rlec(X,N)|L1],[Xs|L1]):-
N1 is N-1, decodifica([rlec(X,N1)|L1],L2).
decodifica([E|L1],[E|L2]):- decodifica(L1,L2).
An example is:
?- decodifica([b,rlec(a,3)],R).
R = [b, a, a, a] ;
But I want to use Peano notation. Any suggestions?
Assuming the following representation for the peano numbers:
zero for the number 0 . succ(zero) for the number 1 . succ(N) for N+1 . You simply have to change your current base case, 1 , to the first peano number, zero . Then, instead of subtracting 1 to N , parts of a succ(N) , from which you are removing successors:
decodifica([],[]).
decodifica([rlec(X,zero)|L1],[X|L2]).
decodifica(L1,L2).
decodifica([rlec(X,succ(N))|L1],[Xs|L1]):-
decodifica([rlec(X,N)|L1],L2).
decodifica([E|L1],[E|L2]):- decodifica(L1,L2).