ref: 85adea62d7e8eee9d0e3525d572325db4e58d21a
dir: pprolog/example.pl
math(A,B,C,D) :- D is A + B + C * A.
parentest :-
1 + 2 * 3 + 4.
parentest :-
(0 * (1 + 2) * 3) * 3 + 4.
likes(bob, ice).
likes(sam, text).
likes(sam, ice).
could_be_friends(Person1, Person2) :-
likes(Person1, Thing1),
likes(Person2, Thing2),
Thing1 = Thing2.
list1(A) :- A = [1,2,3,4].
list2(A) :- A = [a,b|c].
curly(A) :- A = {one,two,three}.
tester(A, B) :- !, A = B.
tester(A, B) :- true.
=(A,A).
length([], zero).
length([Head|Tail], suc(Length)) :-
length(Tail, Length).