Perm.internal_append_nil: def of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/perm.bend as Perm
Lines 110-116 of bend-mathlib@0.8.1.0/perm.bend: https://jend.leeeet.dev/read.txt?path=bend-mathlib@0.8.1.0/perm.bend&start_line=110&end_line=116

import Base

def internal_append_nil(-A: Data, +ys: List<&2, A>) -> {List.append(&2, A, ys, Nil{}) == ys : List<&2, A>}:
  match ys:
    case Nil{}:
      {==}
    case +y <> t:
      %Equal.sym(List<&2, A>, List.append(&2, A, t, Nil{}), t, internal_append_nil(A, t)) : {y <> _ == y <> t : List<&2, A>}
      {==}

Uses (3):
  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