Prologの技芸 10.1節の練習問題

(1)

range(M,N,[M|Ns]) :-
 nonvar(M), nonvar(N), M < N, M1 is M+1, range(M1,N,Ns).
range(M,N,[M|Ns]) :-
 nonvar(M), nonvar(Ns), M1 is M+1, range(M1,N,Ns).
range(N,N,[N]).

(2)

plus(X,Y,Z) :- nonvar(Z), between(0,Z,X), Y is Z-X.