CanPlace

Capability: a B can be written into an already-built T — the carrier-free surface of the place / transfer extensions.

Unlike its siblings this capability has NO derived given: the extensions additionally require T => F[X, B] evidence over the optic's existential X, which a generic optic given does not refine. Construct it explicitly at the seam instead — CanPlace.from(myLens) — and pass it along. See CanGet for the doctrine and the coherence rule.