def append_assoc

bend-collections-laws-math@1.0.0.0 · proofs/lib/list.bend:18

import Base
import bend-collections-laws-math@1.0.0.0/spec/lib/common.bend as SC

18def append_assoc(-A: Data, +xs: List<&2, A>, +ys: List<&2, A>, +zs: List<&2, A>) -> {SC.append(A, SC.append(A, xs, ys), zs) == SC.append(A, xs, SC.append(A, ys, zs)) : List<&2, A>}:
19  match xs:
20    case Nil{}:
21      {==}
22    case Con{+h, +t}:
23      cons_cong(A, h, SC.append(A, SC.append(A, t, ys), zs), SC.append(A, t, SC.append(A, ys, zs)), append_assoc(A, t, ys, zs))