Spec.spass: def of bendtorch@1.3.0.0
Import: import bendtorch@1.3.0.0/spec.bend as Spec
Lines 183-191 of bendtorch@1.3.0.0/spec.bend: https://jend.leeeet.dev/read.txt?path=bendtorch@1.3.0.0/spec.bend&start_line=183&end_line=191

import Base

# one pass of main.bend's tree_sum (ts_pass): neighbours added in pairs, an odd last cell carried up as it is
def spass(xs: List<&2, Sum>) -> List<&2, Sum>:
  match xs:
    case Nil{}:
      Nil{}
    case Con{a, Nil{}}:
      a <> Nil{}
    case Con{a, Con{b, t}}:
      SAdd{a, b} <> spass(t)

Uses (2):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=bendtorch@1.3.0.0/spec.bend&name=Sum