//var unify = require('unify');

var arrayToString = function(arr){

  return "[" + arr.join() + "]";

};

var variable = unify.variable;

var rectangle = unify.box({

  topLeft:[0,0],

  topRight:[1,0],

  bottomLeft:[0,1],

  bottomRight:[1,1]

});

var extractor = unify.box({

  topLeft:variable("topLeft",unify.isNum),

  topRight:variable("topRight",unify.isNum),

  bottomLeft:variable("bottomLeft",unify.isNum),

  bottomRight:variable("bottomRight",unify.isNum)

});

//extract the corners of the rectangle

if (extractor.unify(rectangle)) {

  console.log("topLeft: " + arrayToString(extractor.get("topLeft")));

  console.log("topRight: " + arrayToString(extractor.get("topRight")));

  console.log("bottomLeft: " + arrayToString(extractor.get("bottomLeft")));

  console.log("bottomRight: " + arrayToString(extractor.get("bottomRight")));

}

else {

  console.log("Somthing went wrong. Unification failed!");

}

extractor.rollback();

//The above code will print the following to the console

//"topLeft: [0,0]"

//"topRight: [1,0]"

//"bottomLeft: [0,1]"

//"bottomRight: [1,1]"