def AP.reflect.join
import bend-osdev-array@0.1.0.1/PROOF.bend as PROOFimport Base
507def AP.reflect.join(-T: Data, -xs: Array<T>, -ys: Array<T>, rx: &t: AP.Tree<T> -> {AP.build(T, t) == xs : Array<T>}, ry: &t: AP.Tree<T> -> {AP.build(T, t) == ys : Array<T>}) -> &t: AP.Tree<T> -> {AP.build(T, t) == ANode{xs, ys} : Array<T>}:
508 (tx, ex) = rx
509 (ty, ey) = ry
510 (APNode{tx, ty}, AP.reflect.node(T, tx, ty, xs, ys, ex, ey))