def p_drop_take

bend-osdev-bytes@0.1.1.0 · PROOF.bend:1159

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

1159def p_drop_take(+i: Nat, +j: Nat, +o: B.Octets) -> {B.Octets.drop(i, B.Octets.take(j, o)) == B.Octets.take(Nat.sub(j, i), B.Octets.drop(i, o)) : B.Octets}:
1160  match o:
1161    case B.Octets{+ws}:
1162      %F_take(j, ws) : {B.Octets{B.w8s.drop(i, _)} == B.Octets{B.w8s.take.fast(Nat.sub(j, i), B.w8s.drop(i, ws))} : B.Octets}
1163      %F_take(Nat.sub(j, i), B.w8s.drop(i, ws)) : {B.Octets{B.w8s.drop(i, B.w8s.take(j, ws))} == B.Octets{_} : B.Octets}
1164      Equal.cong(List<&2, B.OctByte>, B.Octets, l => B.Octets{l}, B.w8s.drop(i, B.w8s.take(j, ws)), B.w8s.take(Nat.sub(j, i), B.w8s.drop(i, ws)), off.drop_take(i, j, ws))