Schnorr.sign_r: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend as Schnorr
Lines 130-138 of bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend&start_line=130&end_line=138

import Base
import bend-collections@1.0.0.0/spec/crypto/secp256k1/field.bend as FS
import bend-collections@1.0.0.0/spec/crypto/secp256k1/curve.bend as CV

# R = k' G; k = k' if has_even_y(R), otherwise n - k';
# e = int(hash_challenge(bytes(R) || bytes(P) || m)) mod n
def sign_r(+one: Nat, +d: Nat, +pb: List<&2, U32>, +m: List<&2, U32>, +k0: Nat, ra: CV.SAffine) -> Maybe<&2, List<&2, U32>>:
  match ra:
    case CV.SAffine{rx, +ry}:
      +k = even(n(one), ry, k0)
      +rb = bytes32(rx)
      +e = Nat.mod(CV.os2ip(tagged(tag_challenge(), cat(rb, cat(pb, m)))), n(one))
      sign_fin(one, pb, m, cat(rb, bytes32(FS.madd(n(one), k, FS.mmul(n(one), e, d)))))

Uses (16):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  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.mod
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/curve.bend&name=SAffine
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/curve.bend&name=os2ip
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/field.bend&name=madd
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/field.bend&name=mmul
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend&name=bytes32
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend&name=cat
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend&name=even
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend&name=n
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend&name=sign_fin
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend&name=tag_challenge
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/secp256k1/schnorr.bend&name=tagged