Function defToString

src/compute-engine/engine-scope.ts:145–187

(name: string, def: BoxedDefinition)

  // silent revert for the pop to cover, and the pop must not advance `any`
  // either. This is what keeps
  // a read-only scoped probe — a `Comprehension` count/finiteness scan, a
  // lazy `Filter` emptiness walk — from retiring every `_type`/`_sgn` cache
  // engine-wide: those probes bracket with push/pop per read, and with an
  // unconditional bump each probe invalidated the very caches the enclosing
  // type derivation was filling, so boxing a row that references a
  // comprehension-bound name recomputed the whole subtree per node (Tycho
  // item 181: 872K clean pops and 1.85M wasted type recomputes in ONE
  // canonical box, ~60–90 s per `.type` read).
  const clean =
    context?._assumptionsDirty !== true &&
    context?._anyVersionAtPush === ce._anyVersion &&
    context?._semanticVersionAtPush === ce._semanticVersion &&
    context?._worldVersionAtPush === ce._worldVersion;
  ce._noteStateEvent({
    kind: 'scope-pop',
    assumptionsDirty: context?._assumptionsDirty === true,
    ...(clean ? { clean: true } : {}),
  });
}

export function inScope<T>(
  ce: IComputeEngine,
  scope: Scope | undefined,
  f: () => T
): T {
  if (!scope) return f();

  // Push a temporary eval context to switch to the given scope
  ce._evalContextStack.push({
    lexicalScope: scope,
    name: '',
    assumptions: new ExpressionMap(ce.context?.assumptions ?? []),
  });

  try {
    // During boxing this temporary lexical scope is the correct restart owner
    // for a devolved builtin shadow. Outside boxing, `withScopedRepair()` is a
    // transparent single pass, so evaluation side effects are never repeated.
    return ce._boxingState.withScopedRepair(scope, f);
  } finally {
    const popped = ce._evalContextStack.pop();
    // This transient pop bypasses `discardEvalContext`, so it runs the
    // checkpoint frame-retirement hook itself: a checkpoint taken inside
    // this extent stood on the popped frame and dies with it.
    if (popped !== undefined && ce._checkpointStack.length > 0)
      ce._invalidateCheckpointsOnFrameDiscard(popped);