law take_left

bend-mathlib@0.8.1.0 · list.bend:1077

import Base

1077# Taking the length of the first part of an append gives the first part back.
1078law take_left:
1079  for -a: Quant
1080  for -A: Kind(a)
1081  for xs: List<a, A>
1082  for ys: List<a, A>
1083  {List.take(a, A, List.append(a, A, xs, ys), List.length(a, A, xs)) == xs : List<a, A>}