Limbs.sh_okb: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend as Limbs
Lines 104-113 of bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&start_line=104&end_line=113

import Base
import bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend as C
import bend-collections-laws-crypto@1.0.0.0/proofs/lib/logic.bend as L

def sh_okb(+n: Nat, +xs: List<&2, U32>, +b: Nat, +x: Nat, +e: {okb(n, xs, b) == True{} : Bool}) -> {sh(xs, x) == shn(n, x) : Nat}:
  match n xs:
    case 0n Nil{}:
      {==}
    case 0n Con{y, yt}:
      Empty.absurd({sh(Con{y, yt}, x) == x : Nat}, L.false_true(e))
    case 1n+m Nil{}:
      Empty.absurd({x == shn(1n+m, x) : Nat}, L.false_true(e))
    case 1n+ +m Con{+y, +yt}:
      Equal.cong(Nat, Nat, z => C.shift(8n, z), sh(yt, x), shn(m, x), sh_okb(m, yt, b, x, okb_tail(m, y, yt, b, e)))

Uses (12):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Empty.absurd
  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/proofs/crypto/curve25519/limbs.bend&name=okb
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=okb_tail
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=sh
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend&name=shn
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/lib/logic.bend&name=false_true
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/lib/common.bend&name=shift