Cover.lines.on.box: def of gralha-coverage@0.1.0.1
Import: import gralha-coverage@0.1.0.1/cover.bend as Cover
Lines 1186-1196 of gralha-coverage@0.1.0.1/cover.bend: https://jend.leeeet.dev/read.txt?path=gralha-coverage@0.1.0.1/cover.bend&start_line=1186&end_line=1196

import Base
import gralha-text-scan@0.1.0.1/scan.bend as U

# Zero-length lines (a path's move and close) are ignored; the four real ones must lie on the box.
def lines.on.box(xs: List<&2, CovLine>, +x0: F32, +y0: F32, +x1: F32, +y1: F32, +count: U32) -> Bool:
  match xs:
    case Nil{}: U32.is_eq(count, 4)
    case Con{CovLine{ax, ay, bx, by}, rest}:
      +axx = ax
      +ayy = ay
      +bxx = bx
      +byy = by
      +empty = F32.is_eq(axx, bxx) && F32.is_eq(ayy, byy)
      (empty || line.on.box(axx, ayy, bxx, byy, x0, y0, x1, y1)) && lines.on.box(rest, x0, y0, x1, y1, U.choose(U32, empty, count, (count + 1 : U32)))

Uses (12):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.and
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool.or
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32.is_eq
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.add
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.is_eq
  https://jend.leeeet.dev/definition.txt?path=gralha-coverage@0.1.0.1/cover.bend&name=CovLine
  https://jend.leeeet.dev/definition.txt?path=gralha-coverage@0.1.0.1/cover.bend&name=line.on.box
  https://jend.leeeet.dev/definition.txt?path=gralha-text-scan@0.1.0.1/scan.bend&name=choose