Function definePrimitive

definePrimitive<TArgs extends JsonValue, const TReads extends keyof ContextMap>(
primitive: RulePrimitive<TArgs, TReads>,
): RulePrimitive<TArgs, TReads>
Beta
Identity helper for declaring a primitive. Returns its argument unchanged.

The helper exists so TypeScript can infer TArgs from the annotation on build's parameter, and TReads from the reads tuple. Without it, the args shape must either be repeated as a variable type annotation, or TArgs falls back to its unknown default, discarding the args type at every downstream call site.

Inferring TReads also narrows the predicate's scope.get, so reading a key that is not listed in reads is a compile error.

Does not validate the id namespace, that check happens at runtime inside RuleRegistry.register.
Type Parameters
- TArgs extends JsonValue
- const TReads extends keyof ContextMap
Parameters
- primitive: RulePrimitive<TArgs, TReads>
  The primitive definition.
Returns RulePrimitive<TArgs, TReads>
The same primitive, unchanged.
Example: Inferring the args shape and the readable keys
```
import { definePrimitive } from '@limetech/lime-web-components';

type OlderThanArgs = { days: number };

const olderThan = definePrimitive({
    id: 'limetech.older-than',
    reads: ['limeobject'],
    build:
        ({ days }: OlderThanArgs) =>
        (scope) => {
            // @ts-expect-error 'user' is not listed in reads
            scope.get('user');

            return scope.get('limeobject') !== undefined && days > 0;
        },
});
```

Function definePrimitive

Type Parameters

Parameters

Returns RulePrimitive<TArgs, TReads>

Example: Inferring the args shape and the readable keys

Settings