Deque.step: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/src/containers/deque.bend as Deque
Lines 126-143 of bend-collections@1.0.0.0/src/containers/deque.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&start_line=126&end_line=143

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

def step(~T: Data, d: Deque<T>, op: E.Op<T>) -> Deque<T> & E.Obs<T>:
  match op:
    case E.Length{}:
      obs_nat(~T, length(~T, d))
    case E.PushFront{+x}:
      (push_front(~T, d, x), E.OUnit{})
    case E.PushBack{+x}:
      (push_back(~T, d, x), E.OUnit{})
    case E.PopFront{}:
      obs_item(~T, pop_front(~T, d))
    case E.PopBack{}:
      obs_item(~T, pop_back(~T, d))
    case E.PeekFront{}:
      obs_item(~T, peek_front(~T, d))
    case E.PeekBack{}:
      obs_item(~T, peek_back(~T, d))
    case E.ToList{}:
      obs_list(~T, to_list(~T, d))

Uses (16):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Sigma
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=Deque
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=length
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=obs_item
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=obs_list
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=obs_nat
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=peek_back
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=peek_front
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=pop_back
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=pop_front
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=push_back
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=push_front
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/deque.bend&name=to_list
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/types/deque.bend&name=Obs
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/types/deque.bend&name=Op