ProofCore.unpack_get_i: law of lawful-bytes@0.1.1.0
Import: import lawful-bytes@0.1.1.0/proof_core.bend as ProofCore
Lines 126-130 of lawful-bytes@0.1.1.0/proof_core.bend: https://jend.leeeet.dev/read.txt?path=lawful-bytes@0.1.1.0/proof_core.bend&start_line=126&end_line=130

import Base
import lawful-bytes@0.1.1.0/defs.bend as D

# The same for a U32 index: word i >> 2, byte i & 3.
law unpack_get_i:
  for +ws: List<&2, U32>
  for +i: U32
  {List.get(&2, U32, D.unpack(ws), U32.to_nat(i)) == mb(List.get(&2, U32, ws, U32.to_nat((i >> 2n : U32))), U32.to_nat((i .&. 3 : U32))) : Maybe<&2, U32>}

Uses (16):
  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.get
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Maybe
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.div
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.mod
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.and
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.shrn
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.to_nat
  https://jend.leeeet.dev/definition.txt?path=lawful-bytes@0.1.1.0/defs.bend&name=unpack
  https://jend.leeeet.dev/definition.txt?path=lawful-bytes@0.1.1.0/proof_core.bend&name=mb
  https://jend.leeeet.dev/definition.txt?path=lawful-bytes@0.1.1.0/proof_core.bend&name=unpack_get_n
  https://jend.leeeet.dev/definition.txt?path=lawful-words@0.1.0.0/proof_u32.bend&name=to_nat_and_mask
  https://jend.leeeet.dev/definition.txt?path=lawful-words@0.1.0.0/proof_u32.bend&name=to_nat_shrn