Fact matching more than once for a rule

[devijvers]

define Thing {
  constructor: function(value) {
    this.value = value;
  }
}

rule "some rule" {
   when {
     $1: Thing $1.value == "something";
     $2: Thing;
   }
}

The fact matched by $1 will also be matched by $2, that doesn't feel right in my opinion. Matching typically happens left-to-right, therefore $1 should have priority over $2.

[devijvers]

I've checked Prolog, apparently this is perfectly normal behavior. In Prolog you would have to add $1 = $2 to enforce that both can't be equal. Is this possible with nools constraints?

[doug-martin]

Yes if they are the same exact object then you could do the following

define Thing {
  constructor: function(value) {
    this.value = value;
  }
}

rule "some rule" {
   when {
     $1: Thing $1.value == 'something';
     $2: Thing $2 != $1;
   }
}

[devijvers]

$2: Thing $2 != $1;

Thanks, I've confirmed this to be correct. I'm closing this issue.