Blist.prefix_first: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/proofs/crypto/secp256k1/blist.bend as Blist
Lines 38-45 of bend-collections-laws-crypto@1.0.0.0/proofs/crypto/secp256k1/blist.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/secp256k1/blist.bend&start_line=38&end_line=45

import Base
import bend-collections-laws-crypto@1.0.0.0/spec/crypto/secp256k1/curve.bend as CV
import bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/bytes.bend as B

def prefix_first(n: Nat, bs: List<&2, U32>) -> {B.prefix(n, bs) == CV.first(n, bs) : List<&2, U32>}:
  match n bs:
    case 0n _:
      {==}
    case 1n+k Nil{}:
      {==}
    case 1n+ +k +b <> t:
      Equal.cong(List<&2, U32>, List<&2, U32>, l => b <> l, B.prefix(k, t), CV.first(k, t), prefix_first(k, t))

Uses (6):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Equal.cong
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/crypto/secp256k1/curve.bend&name=first
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/secp256k1/bytes.bend&name=prefix