Perm.isort_by: def of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/perm.bend as Perm
Lines 75-81 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=75&end_line=81

import Base

# Insertion sort by the comparator le.
def isort_by(~A: Data, ~le: A -> A -> Bool, xs: List<&2, A>) -> List<&2, A>:
  match xs:
    case Nil{}:
      Nil{}
    case +x <> t:
      insert_by(~A, ~le, x, isort_by(~A, ~le, t))

Uses (3):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Bool
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=bend-mathlib@0.8.1.0/perm.bend&name=insert_by