LDC-E4108 — A priority naming a rule that does not exist

What it means

Every side of a priority must name a rule declared in the package. A misspelled or missing name leaves an edge pointing at nothing, and a priority over a nonexistent rule never applies. The compiler refuses the package at the edge.

Declare the missing rule, or correct the name on the priority side.

Example

Arxo Law

language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

entity A;
relation p(a: A) kind institutional;
relation q(a: A) kind institutional;
rule r1 defeasible { for a: A; when p(a); then q(a); }
priority e1: r1 > ghost reason demo.diagnostics.r1;

Fix

Arxo Law

language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

entity A;
relation p(a: A) kind institutional;
relation q(a: A) kind institutional;
rule r1 defeasible { for a: A; when p(a); then q(a); }

Engine message

The engine reports this in its own wording:

Output

example.law:9:10: error LDC-E4108: priority references undeclared rule "ghost" (§192)

Related

• Priority — how competing rules are ordered.