Poly1305.canon: def of bend-collections@1.0.0.0
Import: import bend-collections@1.0.0.0/spec/crypto/poly1305.bend as Poly1305
Lines 42-46 of bend-collections@1.0.0.0/spec/crypto/poly1305.bend: https://jend.leeeet.dev/read.txt?path=bend-collections@1.0.0.0/spec/crypto/poly1305.bend&start_line=42&end_line=46

import Base
import bend-collections@1.0.0.0/spec/lib/common.bend as C

# y < 2^130: y itself when y < p, else y - p = (y + 5) - 2^130.
def canon(+y: Nat) -> Nat:
  match y:
    case 0n: 0n
    case 1n+z: pick(C.fits(130n, Nat.add(1n+z, 5n)), 1n+z, C.low(130n, Nat.add(1n+z, 5n)))

Uses (5):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat.add
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/crypto/poly1305.bend&name=pick
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/lib/common.bend&name=fits
  https://jend.leeeet.dev/definition.txt?path=bend-collections@1.0.0.0/spec/lib/common.bend&name=low