def project_length

bend-collections@1.0.0.0 · src/containers/doubly_linked_list.bend:245

import Base
import bend-collections@1.0.0.0/src/containers/types/doubly_linked_list.bend as E

245def project_length(~T: Data, r: DList<T> & E.Obs<T>) -> DList<T> & Nat:
246  match r:
247    case Tuple{s, E.ONat{x}}:
248      (s, x)
249    case Tuple{s, other}:
250      (s, 0n)