Morn will be a library for logical programming in Java.
To build and install morn run mvn install.
A working example looks like this (compare The Art of Prolog):
final Functor father = new Functor("father");
final Functor mother = new Functor("mother");
final Functor male = new Functor("male");
final Functor female = new Functor("female");
final Functor son = new Functor("son");
final Functor daughter = new Functor("daughter");
final Functor grandfather = new Functor("grandfather");
final Constant terach = new Constant("terach");
final Constant abraham = new Constant("abraham");
final Constant nachor = new Constant("nachor");
final Constant haran = new Constant("haran");
final Constant isaac = new Constant("isaac");
final Constant lot = new Constant("lot");
final Constant milcah = new Constant("milcah");
final Constant yiscah = new Constant("yiscah");
final Constant sarah = new Constant("sarah");
final Variable x = new Variable("X");
final Variable y = new Variable("y");
final Variable z = new Variable("z");
final KnowledgeBase kb = Morn.buildKB()
.addFact(father.apply(terach, abraham))
.addFact(father.apply(terach, nachor))
.addFact(father.apply(terach, haran))
.addFact(father.apply(abraham, isaac))
.addFact(father.apply(haran, lot))
.addFact(father.apply(haran, milcah))
.addFact(father.apply(haran, yiscah))
.addFact(mother.apply(sarah, isaac))
.addFact(male.apply(terach))
.addFact(male.apply(abraham))
.addFact(male.apply(nachor))
.addFact(male.apply(haran))
.addFact(male.apply(isaac))
.addFact(male.apply(lot))
.addFact(female.apply(sarah))
.addFact(female.apply(milcah))
.addFact(female.apply(yiscah))
.addRule(son.apply(x, y), father.apply(y, x), male.app(x))
.addRule(daughter.apply(x, y), father.apply(y, x)female.apply(x))
.addRule(grandfather.apply(x, y), father.apply(x, z)father.apply(z, y));
kb.query(son.apply(isaac, abraham));
kb.query(daughter.apply(isaac, abraham));
kb.query(daughter.apply(milcah, haran));
kb.query(grandfather.apply(terach, isaac));Further examples might be found in MornTest.java.