def adv

yaml-for-bend@0.1.1.0 · scan.bend:283

import Base

283def adv(c: Cur) -> Cur:
284  match c:
285    case Cur{s, at, left}:
286      match s:
287        case SNil{}:
288          Cur{SNil{}, at, left}
289        case SCon{h, t}:
290          Cur{t, past(at, h), Nat.sub(left, 1n)}