def last_snoc

bend-collections-laws-math@1.0.0.0 · proofs/lib/list.bend:268

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

268def last_snoc(-A: Data, +xs: List<&2, A>, +x: A) -> {SC.last(A, SC.snoc(A, xs, x)) == Some{x} : Maybe<&2, A>}:
269  match xs:
270    case Nil{}:
271      {==}
272    case Con{h, Nil{}}:
273      {==}
274    case Con{h, Con{+h2, +t2}}:
275      last_snoc(A, Con{h2, t2}, x)