Number.ones: def of bend-collections-laws-math@1.0.0.0
Import: import bend-collections-laws-math@1.0.0.0/spec/math/number.bend as Number
Lines 20-26 of bend-collections-laws-math@1.0.0.0/spec/math/number.bend: https://jend.leeeet.dev/read.txt?path=bend-collections-laws-math@1.0.0.0/spec/math/number.bend&start_line=20&end_line=26

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

# the 1 bits among the k lowest bits of n
def ones(k: Nat, +n: Nat) -> Nat:
  match k:
    case 0n:
      0n
    case 1n+p:
      Nat.add(C.bit(n), ones(p, C.half(n)))

Uses (4):
  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-laws-math@1.0.0.0/spec/lib/common.bend&name=bit
  https://jend.leeeet.dev/definition.txt?path=bend-collections-laws-math@1.0.0.0/spec/lib/common.bend&name=half