Xbits.clamp_okb: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/xbits.bend as Xbits
Lines 158-164 of bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/xbits.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/xbits.bend&start_line=158&end_line=164

import Base
import bend-collections-laws-crypto@1.0.0.0/src/crypto/curve25519/x25519.bend as X
import bend-collections-laws-crypto@1.0.0.0/proofs/lib/nat.bend as N
import bend-collections-laws-crypto@1.0.0.0/proofs/lib/logic.bend as L
import bend-collections-laws-crypto@1.0.0.0/proofs/math/hash/hash.bend as HH
import bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/limbs.bend as LM

def clamp_okb(+k: List<&2, U32>, +e: {LM.okb(32n, k, 255n) == True{} : Bool}) -> {LM.okb(32n, X.clamp(k), 255n) == True{} : Bool}:
  match k:
    case Nil{}:
      Empty.absurd({LM.okb(32n, Nil{}, 255n) == True{} : Bool}, L.false_true(e))
    case Con{+b, +bt}:
      +ha = N.le_trans(v(U32.and(b, 248)), 248n, 255n, HH.and_le32(b, 248), {==})
      clamp_top_okb(31n, Con{U32.and(b, 248), bt}, L.and_intro(Nat.is_le(v(U32.and(b, 248)), 255n), LM.okb(31n, bt, 255n), ha, LM.okb_tail(31n, b, bt, 255n, e)))

Uses (15):
  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=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.is_le
  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=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/xbits.bend&name=clamp_top_okb
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/crypto/curve25519/xbits.bend&name=v
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/lib/logic.bend&name=and_intro
  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/proofs/lib/nat.bend&name=le_trans
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/proofs/math/hash/hash.bend&name=and_le32
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/src/crypto/curve25519/x25519.bend&name=clamp