def off.take_app_le

bend-osdev-bytes@0.1.1.0 · PROOF.bend:847

import Base
import bend-osdev-bytes@0.1.1.0/bytes.bend as B

847def off.take_app_le(+n: Nat, xs: List<&2, B.OctByte>, +ys: List<&2, B.OctByte>) -> {Nat.is_le(n, List.length(&2, B.OctByte, xs)) == True{} : Bool} -> {B.w8s.take(n, List.append(&2, B.OctByte, xs, ys)) == B.w8s.take(n, xs) : List<&2, B.OctByte>}:
848  match n xs:
849    case 0n _:
850      h => {==}
851    case 1n+p Nil{}:
852      h => off.no({B.w8s.take(1n+p, ys) == Nil{} : List<&2, B.OctByte>}, h)
853    case 1n+p Con{x, t}:
854      h => Equal.cong(List<&2, B.OctByte>, List<&2, B.OctByte>, l => Con{x, l}, B.w8s.take(p, List.append(&2, B.OctByte, t, ys)), B.w8s.take(p, t), off.take_app_le(p, t, ys, h))