# Take a calculation from another act

## Intent

I want to use a public result of a neighbouring package.

## Wrong form and why it stays silent

If pub is removed from the owner’s amount, that package still compiles, but the consumer’s lower rejects the reference: LDC-E1105. With the interface alone, without the owner’s rules in the world, the result remains NEITHER. The adapter checks both cases. An extra static mutation below reminds that an import alias is reserved.

```law title="Incorrect form"
import recipe.dependency version "1.0.0" as dep;
pub entity Person;
```

## Correct form

```law
language "law.core" version "0.2";
package recipe.i10 version "1.0.0";
namespace "urn:recipe:i-sources:10";
pub entity Person;
pub relation units(p: Person, count: Integer);
pub relation amount(p: Person, value: Integer);
pub rule Calculate strict { for p: Person; for count: Integer; when units(p, count); then amount(p, count * 7); }
```

## Frozen execution scene

Below is a minimal reproducible scene.

| World and facts | Answer amount/total |
|---|---|
| interface, units(p, 3) | NEITHER |
| merged world, units(p, 3) | TRUE_ONLY, 21 |
| merged world without units(p, 3) | NEITHER |
| owner removed pub from amount | E1105 on consumer lower |

```python
>>> import runpy
>>> checks = runpy.run_path("docs/recipes/i-sources/resources/check.py")
>>> checks["imports"](https://github.com/arxohq/law/blob/master/docs/recipes/i-sources/10)
True
```


Consumer (a separate package; the adapter compiles it with an export context):

```law
language "law.core" version "0.2";
package recipe.consumer10 version "1.0.0";
namespace "urn:recipe:i-sources:10:consumer";
import recipe.i10 version "1.0.0";
relation total(p: recipe.i10::Person, value: Integer);
rule ReadAmount strict { for p: recipe.i10::Person; for v: Integer; when recipe.i10::amount(p, v); then total(p, v); }
```

Interface world:

```lawtest
language "law.core" version "0.2";
package recipe.consumer10 version "1.0.0";
namespace "urn:recipe:i-sources:10:consumer";

test "interface without rules answers neither" {
    given {
        context { legal_time @2026-09-13; decision_time @2026-09-13T09:00:00Z; knowledge_time @2026-09-13T09:00:00Z; timezone "UTC"; }
        assert recipe.i10::units(entity_ref("urn:recipe:i-sources:person"), 3);
    }
    evaluate truth(total(entity_ref("urn:recipe:i-sources:person"), 21));
    expect truth_status == NEITHER;
    expect evaluation_status == COMPUTED;
}
```

World world:

```lawtest
language "law.core" version "0.2";
package recipe.consumer10 version "1.0.0";
namespace "urn:recipe:i-sources:10:consumer";

test "merged world computes twenty-one" {
    given {
        context { legal_time @2026-09-13; decision_time @2026-09-13T09:00:00Z; knowledge_time @2026-09-13T09:00:00Z; timezone "UTC"; }
        assert recipe.i10::units(entity_ref("urn:recipe:i-sources:person"), 3);
    }
    evaluate truth(total(entity_ref("urn:recipe:i-sources:person"), 21));
    expect truth_status == TRUE_ONLY;
    expect evaluation_status == COMPUTED;
}

test "merged world without fact answers neither" {
    given {
        context { legal_time @2026-09-13; decision_time @2026-09-13T09:00:00Z; knowledge_time @2026-09-13T09:00:00Z; timezone "UTC"; }
        
    }
    evaluate truth(total(entity_ref("urn:recipe:i-sources:person"), 21));
    expect truth_status == NEITHER;
    expect evaluation_status == COMPUTED;
}
```

## Counterfactual

The `teaches` mutation reproduces `LDC-E0206`. Additionally the adapter removes pub → E1105, changes the bytes of the pinned owner → E1104, and drops the resolve context → E1104. These are three different refusals, not one “import does not work”.

## Boundary

The page shows the owner of the exports. The consumer and its context are synthetic resources of this same book. An import supplies an interface; participation of rules requires presenting a world.

Here a minimal checkable witness is left.

## Pitfall

An empty dependency world stays silent; pub is added at the owner.