Cover.tree.at: def of gralha-coverage@0.1.0.1
Import: import gralha-coverage@0.1.0.1/cover.bend as Cover
Lines 56-65 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=56&end_line=65

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

def tree.at(t: CovTree, +half: U32, +x: U32, +y: U32) -> F32:
  match t:
    case CovFlat{v}: v
    case CovQuad{a, b, c, d}:
      +left = U32.is_lt(x, half)
      +top = U32.is_lt(y, half)
      +xx = U.choose(U32, left, x, (x - half : U32))
      +yy = U.choose(U32, top, y, (y - half : U32))
      +next = U32.div(half, 2)
      tree.at(U.choose(CovTree, top, U.choose(CovTree, left, a, b), U.choose(CovTree, left, c, d)), next, xx, yy)

Uses (7):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=F32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.div
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.is_lt
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=U32.sub
  https://jend.leeeet.dev/definition.txt?path=gralha-coverage@0.1.0.1/cover.bend&name=CovTree
  https://jend.leeeet.dev/definition.txt?path=gralha-text-scan@0.1.0.1/scan.bend&name=choose