Rate from a table

Intention

I want to pick exactly one rate over non-overlapping ranges.

Putting the 1000 boundary in both rows yields LDC-E8304: the table cannot prove the rows do not overlap.

Correct formFrozen execution sceneBoundary

Incorrect form and why it stays silent

Incorrect form

when x <= 1000 => 10 percent;
when x >= 1000 and x < 2000 => 15 percent;

Both rows accept 1000: unique must reject the overlap rather than take the first row.

Correct form

Arxo Law

language "law.core" version "0.2";
package recipes.l.r01 version "0.1.0";
namespace "urn:recipe:l-calc:01";

decision Rate(x: Integer) -> Decimal {
    table hit unique {
        when x < 1000 => 10 percent;
        when x >= 1000 and x < 2000 => 15 percent;
        otherwise => 20 percent;
    }
}

Frozen execution scene

Facts and choice	Question	Answer
1. base 999	Rate(999)	0.1 / COMPUTED
2. base 1000	Rate(1000)	0.15 / COMPUTED
3. base 1999	Rate(1999)	0.15 / COMPUTED
4. base 2000	Rate(2000)	0.2 / COMPUTED

below first threshold

Arxo Law

test "below first threshold" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }

    }
    evaluate Rate(999);
    expect value == 0.1;
    expect evaluation_status == COMPUTED;

}

first threshold rate

Arxo Law

test "first threshold rate" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }

    }
    evaluate Rate(1000);
    expect value == 0.15;
    expect evaluation_status == COMPUTED;

}

inside middle band

Arxo Law

test "inside middle band" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }

    }
    evaluate Rate(1999);
    expect value == 0.15;
    expect evaluation_status == COMPUTED;

}

second threshold rate

Arxo Law

test "second threshold rate" {
    given {
        context {
            legal_time @2026-09-13;
            decision_time @2026-09-13T09:00:00+05:00;
            knowledge_time @2026-09-13T09:00:00+05:00;
            timezone "Asia/Almaty";
        }

    }
    evaluate Rate(2000);
    expect value == 0.2;
    expect evaluation_status == COMPUTED;

}

Counterfactual

Mutation: when x < 1000 → when x <= 1000; expected LDC-E8304. Additional counterfactuals are shown as separate table rows.

Boundary

The example sets a rate, not a progressive sum; the latter is Progressive scale by brackets.

Pitfall

With hit unique, an overlap is rejected rather than resolved by taking the first row.