4.2.1

• Add support for OCaml 4.06.0
  #154, #155, #156, #159
  (Gabriel Scherer, Fabian, Leonid Rozenberg)

• Consider { with_path = false } when printing record fields
  #157
  (François Pottier)

4.2

• Add support for OCaml 4.05.0.

• Use the ocaml-migrate-parsetree library to support multiple
  versions of OCaml.

• Fix comparison order of fields in records (#136).

• Silence an unused rec flag warning in generated code (#137).

• Monomorphize comparison function for builtin types (#115)

• Raise an error when type nonrec is encountered (#116).

• Display an error message when dynamic package loading fails.

• Add a with_path option to @@deriving to skip the module path
  in generated code (#120).

The homepage for the project has now moved to:
https://github.com/ocaml-ppx/ppx_deriving

4.1

• Fix type error with inheritied polymorphic variant type in
  [@@deriving map].

• Fix incorrect handling of multi-argument constructors in
  [@@deriving show].

• Add API hooks for ppx_type_conv.

4.0

• Show, eq, ord, map, iter, fold: add support for Result.result.

• Ppx_deriving.Arg: use Result.result instead of polymorphic variants.

• Ppx_deriving.sanitize: parameterize over an opened module.

• Add support for [@@deriving] in module type declarations.

• Add support for loading findlib packages instead of just files in
  ppx_deriving_main.

• Treat types explicitly qualified with Pervasives also as builtin.

• Compatibility with statically linked ppx drivers.

3.1

• Show, eq, ord: hygienically invoke functions from referenced modules
  (such as X.pp for X.t when deriving show) to coexist with modules
  shadowing ones from standard library.

• Iter, map, fold: hygienically invoke List and Array functions.

3.0

• Implement hygiene: Ppx_deriving.{create_quoter,quote,sanitize,with_quoter}.

• Show, eq, ord: add support for lazy_t.

• Add support for [@nobuiltin] attribute.

• Add Ppx_deriving.hash_variant.

• Remove allow_std_type_shadowing option.

• Remove Ppx_deriving.extract_typename_of_type_group.

2.1

• Fix breakage occurring with 4.02.2 w.r.t record labels

• Fix prefixed attribute names ([@deriving.foo.attr] and [@foo.attr]).

• Add allow_std_type_shadowing option for eq and show.

2.0

• Add support for open types.

1.1

• New plugin: create.

• Show, eq, ord: handle _.

• Show, eq, ord, map, iter, fold: handle inheriting from a parametric
  polymorphic variant type.

• Make Ppx_deriving.poly_{fun,arrow}_of_type_decl construct functions
  in correct order. This also fixes all derivers with types with
  more than one parameter.

• Add Ppx_deriving.fold_{left,right}_type_decl.

1.0

• Make deriver names lowercase.

• Remove Findlib+dynlink integration. All derivers must now be
  explicitly required.

• Allow shortening [%derive.x:] to [%x:] when deriver x exists.

• Make Ppx_deriving.core_type field optional to allow ignoring
  unsupported [%x:] shorthands.

• Add support for [@@deriving foo { optional = true }] that does
  not error out if foo is missing, useful for optional dependencies.

• Rename ~name and ~prefix of Ppx_deriving.attr and
  Ppx_deriving.Arg.payload to ~deriver.

• Renamed Ppx_deriving.Arg.payload to get_attr.

• Add Ppx_deriving.Arg.get_expr and get_flag.

0.3

• Show, Eq, Ord, Iter, Fold: handle ref.

• Show: handle functions.

• Show: include break hints in format strings.

• Show: pull fprintf into local environment.

• Show: add [@polyprinter] and [@opaque].

• Add Ppx_deriving.Arg.expr.

0.2

• New plugins: Enum, Iter, Map, Fold.

• All plugins: don't concatenate affix if type is named t.

• Add [%derive.Foo:] shorthand.

• Show, Eq, Ord: add support for list, array, option.

• Show: include full module path in output, including for types with manifest.

• A lot of changes in Ppx_deriving interface.

0.1

• Initial release.