package ppx_sexp_conv

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[@@deriving] plugin to generate S-expression conversion functions


Dune Dependency






  • Depend on ppxlib instead of (now deprecated) ppx_core, ppx_driver and ppx_metaquot.


  • Added new [@@deriving sexp] record-field attribute, [@sexp.omit_nil], for a field that is omitted if its sexp representation is ().

  • Improved [%sexp_of: 'a] and [%of_sexp: 'a] to not expose variable names intended for internal use.



  • Fix generator for polymorphic types where var names clashes with type name: type 't t = ...


  • Clean up the documentation for sexplib, modernizing it to include ppx_sexp_conv, and breaking up the documentation between sexplib and ppx_sexp_conv. Also changed the formatting to use org-mode, so it will render properly on github. Markdown doesn't render well by default, unless you use quite different conventions about linebeaks.


  • Trying to improve the tests in ppx_sexp_conv because they are a mess. At least all tests are automatic now. And more things are tested like the sexpification of exceptions.

  • Update to follow Type_conv and Ppx_core evolution.

  • Make ppx_sexp_conv correctly handle aliases to polymorphic variants:

    type t = A @@deriving sexptype u = t@@deriving sexptype v = u | B @@deriving sexp

    Before, v_of_sexp would never manage to read B. This problem is now fixed if you use sexp_polyonuinstead ofsexp, and if you don't, you get an "unbound value __u_of_sexp__". People should use sexp_polywhen they have a polymorphic variant type that is not syntactically a polymorphic variant, but in practice it's simpler to replacesexpbysexp_poly` when faced with the error above.

    The need for sexp_poly should happen only in one new case: an implementation says type u = t @@deriving sexpbut the interface says `type u =A @@deriving sexp. (the old case where it was already needed is when you have an interface that says `type u = t `@@deriving sexp and in some other implementation you try to say type t = That_module.t | A `@@deriving sexp``).


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