LDC-E8304 — Decision shape the engine does not support

What it means

A decision table row must produce a value the table can actually compare and return: the output type has to match the declared return type of the decision, and the guard language covers only the comparisons the engine can prove things about. When a row returns a value of the wrong kind — money where a quantity was declared, for instance — or asks for reasoning the engine does not implement, the compiler stops at the row instead of guessing.

Aligning the row outputs with the declared return type is the usual fix; a guard the engine cannot prove needs rewriting in simpler terms.

Example

Arxo Law

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

decision Wrong(staff: Integer) -> Quantity {
  table hit unique { when staff >= 10 => 500 KZT; otherwise => 0 kg; }
}

Fix

Arxo Law

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

decision Load(staff: Integer) -> Quantity {
  table hit unique { when staff >= 10 => 500 kg; otherwise => 0 kg; }
}

Engine message

The engine reports this in its own wording:

Output

example.law:6:42: error LDC-E8304: decision "Wrong": invalid hit policy configuration: row output has type Money, but decision return type is Quantity

Related

• LDC-E8301 — hit policies and row guards.