law drop_left

bend-mathlib@0.8.1.0 · list.bend:1093

import Base

1093# Dropping the length of the first part of an append gives the second part.
1094law drop_left:
1095  for -a: Quant
1096  for -A: Kind(a)
1097  for xs: List<a, A>
1098  for ys: List<a, A>
1099  {List.drop(a, A, List.append(a, A, xs, ys), List.length(a, A, xs)) == ys : List<a, A>}