BackwardLAWS.lookup_unknown: law of bendtorch-core@0.1.0.0
Import: import bendtorch-core@0.1.0.0/src/autograd/backward_LAWS.bend as BackwardLAWS
Lines 326-331 of bendtorch-core@0.1.0.0/src/autograd/backward_LAWS.bend: https://jend.leeeet.dev/read.txt?path=bendtorch-core@0.1.0.0/src/autograd/backward_LAWS.bend&start_line=326&end_line=331

import Base
import bendtorch-core@0.1.0.0/src/autograd/backward.bend as Backward

law lookup_unknown:
  for -A: Data
  for +items: List<&2, A>
  for +id: Nat
  for outside: {Nat.is_lt(id, List.length(&2, A, items)) == False{} : Bool}
  {Backward.lookup(A, items, id) == None{} : Maybe<&2, A>}

Uses (8):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List.length
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.is_lt
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/autograd/backward.bend&name=lookup
  https://jend.leeeet.dev/definition.txt?path=bendtorch-core@0.1.0.0/src/autograd/backward_PROOF.bend&name=find_unknown