List.find_append_sym: law of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/list.bend as List
Lines 3099-3105 of bend-mathlib@0.8.1.0/list.bend: https://jend.leeeet.dev/read.txt?path=bend-mathlib@0.8.1.0/list.bend&start_line=3099&end_line=3105

import Base

# Finding in an append finds in the first part, or else in the second, reversed to rewrite toward the simple side.
law find_append_sym:
  for ~A: Data
  for ~f: A -> Bool
  for xs: List<&2, A>
  for ys: List<&2, A>
  {Maybe.or(&2, A, List.find(~A, ~f, xs), List.find(~A, ~f, ys)) == List.find(~A, ~f, List.append(&2, A, xs, ys)) : 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=Equal.sym
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List.append
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List.find
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe.or
  https://jend.leeeet.dev/definition.txt?path=bend-mathlib@0.8.1.0/list.bend&name=find_append