Survival.head_is_ref: def of unified-nsga-iii@0.2.2.0
Import: import unified-nsga-iii@0.2.2.0/survival.bend as Survival
Lines 737-742 of unified-nsga-iii@0.2.2.0/survival.bend: https://jend.leeeet.dev/read.txt?path=unified-nsga-iii@0.2.2.0/survival.bend&start_line=737&end_line=742

import Base

def head_is_ref(bags: List<&2, Bag>, +r: Nat) -> Bool:
  match bags:
    case Nil{}:
      False{}
    case Bag{+ref, count, members} <> _:
      Nat.is_eq(ref, r)

Uses (5):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  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.is_eq
  https://jend.leeeet.dev/definition.txt?path=unified-nsga-iii@0.2.2.0/survival.bend&name=Bag