The handle a Lazy parameter receives: an argument's subtree, anchored at the calling
cell, that has either not been evaluated yet or has been evaluated already.
Remarks
The brand exists for the same reason Lambda's does — the value-layer sites (coercion,
the operators, a range's typed read, a cell's final value) RECOGNIZE a handle and refuse it, so
that one can never reach a grid, a spill or a named-formula result. A handle is only ever a
live call's argument.
Evaluates the argument and answers its value, forcing the subtree where the engine deferred
it and answering the value it already has where it declined to.
Forced at most once: a second call answers the same value.
The handle a Lazy parameter receives: an argument's subtree, anchored at the calling cell, that has either not been evaluated yet or has been evaluated already.
Remarks
The brand exists for the same reason Lambda's does — the value-layer sites (coercion, the operators, a range's typed read, a cell's final value) RECOGNIZE a handle and refuse it, so that one can never reach a grid, a spill or a named-formula result. A handle is only ever a live call's argument.