Bucklescript PPX which generates JSON serializers and deserializers for user-defined types.
Example:
/* Define types */
[@decco] type variant('a) = A | B(int) | C(int, 'a);
type dict = Js.Dict.t(string);
[@decco] type mytype = {
s: string,
i: int,
o: option(int),
complex: array(option(list(variant(string)))),
[@decco.default 1.0] f: float,
[@decco.key "other_key"] otherKey: string,
magic: [@decco.codec Decco.Codecs.magic] dict,
};
/* Use <typename>_encode to encode */
let encoded = mytype_encode({
s: "hello",
i: 12,
o: None,
complex: [| Some([ C(25, "bullseye") ]) |],
f: 13.,
otherKey: "other",
magic: Js.Dict.fromArray([|("key","value")|]),
});
Js.log(Js.Json.stringifyWithSpace(encoded, 2));
/* {
"s": "hello",
"i": 12,
"o": null,
"complex": [ [ ["C", 25, "bullseye"] ] ],
"f": 13,
"other_key": "other",
"magic": { "key": "value" }
} */
/* Use <typename>_decode to decode */
let { s, i, o, complex, f, otherKey, magic } =
mytype_decode(encoded)
|> Belt.Result.getExn;
I've been using it for personal projects for a while, but it's never been used for anything important, so YMMV.
- Install package
npm i @ryb73/decco
- Update your
bsconfig.json
{
...,
"bs-dependencies": [ "@ryb73/decco" ],
"ppx-flags": [ "@ryb73/decco/ppx/ppx_decco.sh" ],
...
}
Adding ppx_decco
to ppx-flags
will enable the PPX. Adding decco to bs-dependencies
is required because the code generated by the PPX references the Decco
module.
See __tests__/test.re
for some examples.
Applies to: type declarations, type signatures
Indicates that an encoder and decoder should be generated for the given type.
Applies to: type declarations, type signatures
Indicates than an encoder (but no decoder) should be generated for the given type.
Applies to: type declarations, type signatures
Indicates than an decoder (but no encoder) should be generated for the given type.
Applies to: type expressions
Specifies custom encoders and decoders for the type. Note that both an encoder and decoder must be specified, even if the type expression is within a type for which [@decco.encode] or [@decco.decode] was specified.
[@decco] type t = [@decco.codec (fancyEncoder, fancyDecoder)] fancyType;
Applies to: record fields
By default, Reason record fields map to JS object fields of the same name. Use [@decco.key] to specify a custom JS field name. Useful if the JS field name is invalid as a Reason record field name.
[@decco]
type record = {
[@decco.key "other_key"] otherKey: string,
};
Applies to: record fields
Default: Js.Json.null
When decoding a record, the default value will be used for keys that are missing from the JSON object being decoded.
[@decco] type record = {
[@decco.default "def"] s: string,
};
let {s} = Js.Json.parseExn("{}") |> record_decode |> Belt.Result.getExn;
Js.log(s); /* def */