def pop_front_ready

bend-collections@1.0.0.0 · src/containers/deque.bend:68

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

68def pop_front_ready(~T: Data, d: Deque<T>) -> Deque<T> & Result<&2, &2, E.Error, T>:
69  match d:
70    case DE{Nil{}, b, nf, nb}:
71      (DE{Nil{}, b, nf, nb}, Fail{E.EmptyDeque{}})
72    case DE{Con{x, f}, b, nf, nb}:
73      (DE{f, b, Nat.sub(nf, 1n), nb}, Done{x})