List.map_drop_sym: law of bend-mathlib@0.8.1.0
Import: import bend-mathlib@0.8.1.0/list.bend as List
Lines 2635-2642 of bend-mathlib@0.8.1.0/list.bend: https://jend.leeeet.dev/read.txt?path=bend-mathlib@0.8.1.0/list.bend&start_line=2635&end_line=2642

import Base

# Mapping commutes with dropping: map f (drop n xs) = drop n (map f xs), reversed to rewrite toward the simple side.
law map_drop_sym:
  for ~A: Type
  for ~B: Type
  for ~f: A -> B
  for xs: List<A>
  for n: Nat
  {List.drop(&1, B, List.map(~A, ~B, ~f, xs), n) == List.map(~A, ~B, ~f, List.drop(&1, A, xs, n)) : List<B>}

Uses (6):
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Equal.sym
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List.drop
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=List.map
  https://jend.leeeet.dev/definition.txt?path=Base/base.bend&name=Nat
  https://jend.leeeet.dev/definition.txt?path=bend-mathlib@0.8.1.0/list.bend&name=map_drop