Js_of_ocaml.JsonUnsafe IO. (See Deriving_Json for typesafe IO)
val output : 'a -> Js.js_string Js.tMarshal any OCaml value into this JSON representation.
val unsafe_input : Js.js_string Js.t -> 'aUnmarshal a string in JSON format as an OCaml value (unsafe but fast !).
Raises Failure under the wasm_of_ocaml backend, where the encoding of OCaml values is ambiguous (integers and floats both map to numbers).