def spec_rev_rev

bend-collections-laws-math@1.0.0.0 · proofs/lib/list.bend:198

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

198def spec_rev_rev(-A: Data, +xs: List<&2, A>) -> {SC.reverse(A, SC.reverse(A, xs)) == xs : List<&2, A>}:
199  match xs:
200    case Nil{}:
201      {==}
202    case Con{+h, +t}:
203      Equal.trans(List<&2, A>, SC.reverse(A, SC.snoc(A, SC.reverse(A, t), h)), Con{h, SC.reverse(A, SC.reverse(A, t))}, Con{h, t},
204        rev_snoc(A, SC.reverse(A, t), h), cons_cong(A, h, SC.reverse(A, SC.reverse(A, t)), t, spec_rev_rev(A, t)))