Poly1305.absorb: def of bend-collections-laws-crypto@1.0.0.0
Import: import bend-collections-laws-crypto@1.0.0.0/spec/crypto/poly1305.bend as Poly1305
Lines 105-111 of bend-collections-laws-crypto@1.0.0.0/spec/crypto/poly1305.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/crypto/poly1305.bend&start_line=105&end_line=111

import Base

# for each block: n = le_bytes_to_num(block | [0x01]); a += n; a = (r * a) % p
def absorb(bs: List<&2, List<&2, U32>>, +r: Nat, a: Nat) -> Nat:
  match bs:
    case Nil{}: a
    case b <> rest:
      +n = le_num(List.append(&2, U32, b, [1]))
      absorb(rest, r, modp(Nat.mul(r, Nat.add(a, n))))

Uses (8):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List.append
  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=Base/base.bend&name=Nat.mul
  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/spec/crypto/poly1305.bend&name=le_num
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-crypto@1.0.0.0/spec/crypto/poly1305.bend&name=modp