Okm.length_append: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/proofs/crypto/kdf/okm.bend as Okm
Lines 69-75 of bend-collections-laws-crypto@1.0.0.0/proofs/crypto/kdf/okm.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/kdf/okm.bend&start_line=69&end_line=75

import Base

def length_append(+xs: List<&2, U32>, +ys: List<&2, U32>) -> {List.length(&2, U32, List.append(&2, U32, xs, ys)) == Nat.add(List.length(&2, U32, xs), List.length(&2, U32, ys)) : Nat}:
  match xs:
    case Nil{}:
      {==}
    case +x <> +rest:
      %length_append(rest, ys) : {1n+List.length(&2, U32, List.append(&2, U32, rest, ys)) == 1n+_ : Nat}
      {==}

Uses (6):
  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.length
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32