List.length_drop: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/proofs/lib/list.bend as List
Lines 255-264 of bend-collections-laws-crypto@1.0.0.0/proofs/lib/list.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/lib/list.bend&start_line=255&end_line=264

import Base
import bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend as SC

def length_drop(-A: Data, +xs: List<&2, A>, +k: Nat) -> {SC.length(A, List.drop(&2, A, xs, k)) == Nat.sub(SC.length(A, xs), k) : Nat}:
  match xs k:
    case Nil{} 0n:
      {==}
    case Nil{} 1n+p:
      {==}
    case Con{x, t} 0n:
      {==}
    case Con{x, +t} 1n+p:
      length_drop(A, t, p)

Uses (5):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List.drop
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.sub
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend&name=length