String.is_empty_append_sym: law of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/string.bend as String
Lines 656-660 of bend-mathlib@0.8.1.0/string.bend: https://jend.leeeet.dev/read.txt?path=bend-mathlib@0.8.1.0/string.bend&start_line=656&end_line=660

import Base

# An append is empty exactly when both parts are, reversed to rewrite toward the simple side.
law is_empty_append_sym:
  for a: String
  for -b: String
  {Bool.and(String.is_empty(a), String.is_empty(b)) == String.is_empty(String.append(a, b)) : Bool}

Uses (7):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.and
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Equal.sym
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.append
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=String.is_empty
  https://jend.leeeet.dev/definition.txt?path=bend-mathlib@0.8.1.0/string.bend&name=is_empty_append