Perm.perm_dup: def of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/perm.bend as Perm
Lines 63-65 of bend-mathlib@0.8.1.0/perm.bend: https://jend.leeeet.dev/read.txt?path=bend-mathlib@0.8.1.0/perm.bend&start_line=63&end_line=65

import Base
import bendlib-kernel-list@1.0.0.0/list.bend as K

# A Perm hypothesis in existential form is reusable.
def perm_dup(-A: Data, -xs: List<&2, A>, -ys: List<&2, A>, +h: K.perm(A, xs, ys)) -> K.perm(A, xs, ys) & K.perm(A, xs, ys):
  (h, h)

Uses (4):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Pair
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Sigma
  https://jend.leeeet.dev/definition.txt?path=bendlib-kernel-list@1.0.0.0/list.bend&name=perm