Util.nats_sum: def of unified-nsga-iii@0.2.2.0
Import: import unified-nsga-iii@0.2.2.0/util.bend as Util
Lines 103-109 of unified-nsga-iii@0.2.2.0/util.bend: https://jend.leeeet.dev/read.txt?path=unified-nsga-iii@0.2.2.0/util.bend&start_line=103&end_line=109

import Base

# Sum of a Nat histogram. Used to lock mid-split count conservation.
def nats_sum(xs: List<&2, Nat>) -> Nat:
  match xs:
    case Nil{}:
      0n
    case +x <> rest:
      Nat.add(x, nats_sum(rest))

Uses (3):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  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