d8

08/part1.pl

@@ -0,0 +1,16 @@
+:- op(700, xfx, l).
+:- op(700, xfx, r).
+
+From l To :- From to To-_.
+From r To :- From to _-To.
+
+answer(Answer) :- path([], aaa, Path), length(Path, Answer).
+
+path(_, zzz, []) :- !.  % getting full path instead of just length for debugging
+path(Directions, From, [Move | Cdr]) :-
+    next_step(Directions, Move, Remain),
+    G =.. [Move, From, To], G,
+    path(Remain, To, Cdr).
+
+next_step([Move | Remain], Move, Remain).
+next_step([], Move, Remain) :- direction(Str), atom_chars(Str, [Move | Remain]).