[wtetzner]

> that he can transport them between environments, possibly remotely, possibly written in different programming languages

This is pretty easily solved in static languages with "serializable" interfaces, which can usually be automatically derived. E.g., in Rust, you can use #[derive(Serializable,Deserializable)], in OCaml, you can use [@@deriving sexp]. This also allows you to know at compile time which types can safely be serialized. In Clojure, if you have a type that contains an InputStream of some sort, it's not reasonable to serialize it. But you won't find out until runtime, when you happen to have an instance of that map with the InputStream.