I think the problem is here: for color in self.domains[var]: if not self._valid(var, color): continue self.map[var].color = color for key in node.neighbors: if color in self.domains[key]: self.domains[key].remove(color) # This is potentially bad. if key == var when self.domains[key].remove(color) is called, you change the size of the set you’re currently iterating over. You can avoid this … Read more
There is a lot of excellent material available on the web once you get in the groove, but the links below are (IMO) good starting points (the ones I used). Programming with Constraints: An Introduction – (Course website) Programming with Constraints: An Introduction – (Google book) Online Guide to Constraint Programming
This can be done (at least in some cases) with compiler internals import scala.language.experimental.macros import scala.reflect.internal.util import scala.reflect.macros.{blackbox, contexts} object Macros { def allImplicits[A]: List[String] = macro impl[A] def impl[A: c.WeakTypeTag](c: blackbox.Context): c.Tree = { import c.universe._ val context = c.asInstanceOf[contexts.Context] val global: context.universe.type = context.universe val analyzer: global.analyzer.type = global.analyzer val callsiteContext = context.callsiteTyper.context … Read more
According to Wikipedia, the following versions of Prolog have Java interfaces. I’ve linked to the main pages for them: BProlog Ciao Prolog SICStus Prolog SWI Prolog TuProlog (implemented in Java) LPA Prolog Good luck with your search!
Here’s a solution in Python based on constraint-programming: from constraint import AllDifferentConstraint, InSetConstraint, Problem # variables colors = “blue red green white yellow”.split() nationalities = “Norwegian German Dane Swede English”.split() pets = “birds dog cats horse zebra”.split() drinks = “tea coffee milk beer water”.split() cigarettes = “Blend, Prince, Blue Master, Dunhill, Pall Mall”.split(“, “) # … Read more