I need to generate a value with a different type from my passed type. This is the first time I write on ocaml-like, and for example, in a familiar me haskell I would use Data.Generics. How I have understood I need to use decorator and ppx. I wrote simple example
let recordHandler = (loc: Location.t, _recFlag: rec_flag, _t: type_declaration, fields: list(label_declaration)) => {
let (module Builder) = Ast_builder.make(loc);
let test = [%str
let schema: Schema = { name: "", _type: String, properties: [] }
]
let moduleExpr = Builder.pmod_structure(test);
[%str
module S = [%m moduleExpr]
]
}
let str_gen = (~loc, ~path as _, (_rec: rec_flag, t: list(type_declaration))) => {
let t = List.hd(t)
switch t.ptype_kind {
| Ptype_record(fields) => recordHandler(loc, _rec, t, fields);
| _ => Location.raise_errorf(~loc, "schema is used only for records.");
};
};
let name = "my_schema";
let () = {
let str_type_decl = Deriving.Generator.make_noarg(str_gen);
Deriving.add(name, ~str_type_decl) |> Deriving.ignore;
};
And
open Ppxlib;
let _ = Driver.run_as_ppx_rewriter()
But in using in rescript code
module User = {
@deriving(my_schema)
type my_typ = {
foo: int,
};
};
I caught:
schema is not supported
. And I made myself sure me to connect it right when I had changed @deriving(my_schema) for @deriving(abcd) and @deriving(sschema). I got different error
Ppxlib.Deriving: 'abcd' is not a supported type deriving generator.
And my last experiment was to copy past existing library deriving accessors . ppx_accessor I copied-pasted it and renamed for accessors_2. And I got same error such as experiment.
accessors_2 is not supported
Also I haven't found examples "ppx rescript". Can you please help me. What am I doing wrong (ALL , I know)
