LDC-E1326 — Map over a non-enum domain

What it means

A map proves totality over declared membership: both ends must be enumerations of the package, so every member is known and every row lands somewhere. A domain or codomain that is not a package enum — an entity, a type alias, anything else — gives the map no membership to be total over, and the compiler stops at the offending end.

The repair is to declare the enumeration, or to point the map at one that exists. Rows that name non-members, or the same member twice, are refused by the same check once the ends resolve.

Example

Arxo Law

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

enum Harmony {
    Zhuan;
    Zhinishke;
}
entity Tenant;
map broken_map: Tenant -> Harmony {
    Zhuan => Zhuan;
}

Fix

Arxo Law

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

enum Harmony {
    Zhuan;
    Zhinishke;
}
map full_map: Harmony -> Harmony {
    Zhuan => Zhuan;
    Zhinishke => Zhinishke;
}

Engine message

The engine reports this in its own wording:

Output

example.law:10:17: error LDC-E1326: map "broken_map": domain "Tenant" is not an enum of this package; totality is proven over the declared membership, and the §23 import context does not carry a foreign package's membership (§46.1)

Related

• Vocabulary — how names are declared and which positions take them.