Stack.step: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/src/containers/stack.bend as Stack
Lines 52-63 of bend-collections@1.0.0.0/src/containers/stack.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&start_line=52&end_line=63

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

def step(~T: Data, q: Stack<T>, op: E.Op<T>) -> Stack<T> & E.Obs<T>:
  match op:
    case E.Length{}:
      obs_nat(~T, length(~T, q))
    case E.Push{+x}:
      (push(~T, q, x), E.OUnit{})
    case E.Pop{}:
      obs_item(~T, pop(~T, q))
    case E.Peek{}:
      obs_item(~T, peek(~T, q))
    case E.ToList{}:
      obs_list(~T, to_list(~T, q))

Uses (13):
  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/stack.bend&name=Stack
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&name=length
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&name=obs_item
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&name=obs_list
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&name=obs_nat
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&name=peek
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&name=pop
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&name=push
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/stack.bend&name=to_list
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/types/stack.bend&name=Obs
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/src/containers/types/stack.bend&name=Op