Ppx_type_directed_value is a ppx that does[@@deriving]-stylegeneration of type-directed values based on user-provided modules. Theuser-provided modules tellppx_type_directed_value how to composetype-directed values (for example, combine type-directed values of thefields of a record to form a type-directed value for the recorditself).

This allows a wide variety of PPXs such asppx_sexp_conv,ppx_compare,ppx_enumerate, etc. to be implemented withppx_type_directed_value, but with some runtime cost.

This PPX currently supports deriving type-directed values for records, ordinary& polymorphic variants and tuples. It also supports custom user-defined attributeson record and variant fields.