Module Pa_deriving_Json

module Pa_deriving_Json: sig .. end

module Json_typ : sig

  type a = typ

  val to_string : a -> string

  val from_string : string -> a

  ...

end

val register_predefs : Pa_deriving_common.Type.qname -> Pa_deriving_common.Type.qname -> unit

register_predefs typeA typeB tells the syntax extension that typeB is an alias for typeA. The extension syntax will then use the deriving_json implementation of typeB in place of typeA's one.

Important note: TypeB does NOT HAVE TO actually exists.

In practive, you may need to use this in the following cases:

• use deriving_json on types from external libraries that do not use deriving
• use deriving_json on abstract types