Rand.len64: def of bend-collections-laws-math@1.0.0.0
Import: import bend-collections-laws-math@1.0.0.0/src/math/random/rand.bend as Rand
Lines 285-291 of bend-collections-laws-math@1.0.0.0/src/math/random/rand.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-math@1.0.0.0/src/math/random/rand.bend&start_line=285&end_line=291

import Base
import bend-collections-laws-math@1.0.0.0/src/math/u64.bend as W
import bend-collections-laws-math@1.0.0.0/src/math/w64.bend as X

# the length as a 64-bit word
def len64(-A: Data, xs: List<&2, A>) -> W.U64:
  match xs:
    case Nil{}:
      W.U64{0, 0}
    case Con{x, rest}:
      X.add(len64(A, rest), W.U64{1, 0})

Uses (3):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-math@1.0.0.0/src/math/u64.bend&name=U64
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-math@1.0.0.0/src/math/w64.bend&name=add