How to create a copy of a record type with mutable fields

Learning
1

I’m creating a terminal_io struct which has a large number of mutable fields. Before modifying them, I want to create a copy of the struct in order to be able to restore it later. Currently I’m making a duplicate call to Unix.tcgetattr:

    let savedTio = Unix.tcgetattr Unix.stdin in
    let tio = Unix.tcgetattr Unix.stdin in

I know you can create a copy with modified variables e.g. with:

    let tio = Unix.tcgetattr Unix.stdin in
    let savedTio = { tio with ... = ... } in

But I don’t want to modify any values.

Is there a better way to do this?