You can take a look at Yield Prolog. Yield Prolog uses yield keyword in C# (and Python, and JavaScript) and custom Variable class to simulate Prolog machine. This way, you get a Prolog API in your favourite language. You don’t need to connect your main language with P# or similiar projects.
The interactive gprolog interpreter runs queries against a loaded list of predicates, that is why you get the existence_error exception. You will have to load your predicates into it, either by using an IDE that does the loading for you or doing it manually. Here’s one approach: | ?- [user]. compiling user for byte code… … Read more
(Note: this answer is somewhat of a guess) Consider how Prolog determines whether f(a,c) is true or not. It checks the first rule, f(a,b), and doesn’t find a match, but the second rule, f(a,c) matches. Therefore, f(a,c) is true. Furthermore, since there are no more rules for f, there is no point in allowing a … Read more
Prior to the WAM, there was the ZIP by Clocksin. Its design is still very interesting. SWI-Prolog uses it. And also B-Prolog has slowly migrated from a WAM design towards the ZIP. Of course, on that way many new innovations were developed. Another alternative is the VAM. A comparison as of 1993 is: http://www.complang.tuwien.ac.at/ulrich/papers/PDF/binwam-nov93.pdf In … Read more
I am writing this answer, because the best answer yet was in a comment by lurker. I want to have it show up as an actual answer. Your code is not working, because you’re doing R1 is R+1 when R isn’t instantiated in the case not_number([X|T], R). Your recursive case is strung a little backwards. … Read more
If your file is called foo.pl, you can include it using :- [foo]. or, equivalently and a bit more explicit :- consult(foo). or, if you’re worried it may be loaded several times in a larger app :- ensure_loaded(foo). or, if you’re using full-blown modules :- use_module(foo). though the exact name of the last predicate differs … Read more
Solution: member(X, [Y|T]) :- X = Y; member(X, T). Demonstration: ?- member(a, []). fail. ?- member(a, [a]). true ; fail. ?- member(a, [b]). fail. ?- member(a, [1, 2, 3, a, 5, 6, a]). true ; true ; fail. How it works: We are looking for an occurrence of the first argument, X, in the the … Read more
iso_dif/2 is much simpler to implement than a comparison: The built-in \= operator is available You now exactly what arguments to provide to\= Definition Based on your comments, the safe comparison means that the order won’t change if variables in both subterms are instanciated. If we name the comparison lt, we have for example: lt(a(X), … Read more
First try! The following code is based on the meta-predicates tfilter/3 and tpartition/4, the monotone if-then-else control construct if_/3, the reified unary logical connective not_t/3, and the reified term equality predicate (=)/3: different([],[_|_]). different([X|Xs0],Ys0) :- tpartition(=(X),Ys0,Es,Ys1), if_(Es=[], true, (tfilter(not_t(=(X)),Xs0,Xs1),different(Xs1,Ys1))). Sample query: ?- different([A,B],[X,Y]). A=Y , dif(B,Y), X=Y ; A=X , B=X , dif(X,Y) ; A=X … Read more
I don’t know what do you mean by “not equal” (does not unify?), but you could try these: X \= Y not(X = Y) \+ (X = Y)