# 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.

## Incorrect form and why it stays silent

```text title="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

```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` |

```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;
    
}
```

```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;
    
}
```

```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;
    
}
```

```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](/recipes/l-calc/progressive-scale/).

## Pitfall

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