Graphorin API reference v0.1.0

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Graphorin API reference / @graphorin/core / / assertNever

Function: assertNever()

function assertNever(value, message?): never;

Defined in: packages/core/src/utils/assert-never.ts:22

Exhaustiveness helper. Place at the end of a switch (...) over a discriminated union: TypeScript narrows the operand to never if every variant is handled. Adding a new variant later turns the call site into a compile error — the regression net for our event unions.

Parameters

Parameter	Type
value	never
message?	string

Returns

never

Example

function describe(event: AgentEvent): string {
  switch (event.type) {
    case 'agent.start': return 'started';
    case 'agent.end':   return 'ended';
    // ... every other variant ...
    default:
      return assertNever(event, 'Unhandled AgentEvent variant');
  }
}

Stable