law append_assoc_sym

bend-mathlib@0.8.1.0 · list.bend:2148

import Base

2148# Append is associative: (xs ++ ys) ++ zs = xs ++ (ys ++ zs), reversed to rewrite toward the simple side.
2149law append_assoc_sym:
2150  for -a: Quant
2151  for -A: Kind(a)
2152  for xs: List<a, A>
2153  for -ys: List<a, A>
2154  for -zs: List<a, A>
2155  {List.append(a, A, xs, List.append(a, A, ys, zs)) == List.append(a, A, List.append(a, A, xs, ys), zs) : List<a, A>}