Getting Started

Define the JSON shape explicitly with hand-written traits.

Encode by implementing SagaJson.Encode.ToJson.
Decode by implementing SagaJson.Decode.FromJson.
Compose impls from SagaJson.Encode builders and SagaJson.Decode combinators.
Use E.serialize and D.deserialize at string boundaries.

import Std.Fail (Fail)
import SagaJson as J
import SagaJson.Encode as E
import SagaJson.Encode (ToJson)
import SagaJson.Decode as D
import SagaJson.Decode (FromJson)

record Person {
  name: String,
  age: Int,
  email: Maybe String,
} deriving (Debug)

impl ToJson for Person {
  to_json p =
    E.object [
      ("name", to_json p.name),
      ("age", to_json p.age),
      ("email", to_json p.email),
    ]
}

impl FromJson for Person needs {Fail J.Error} {
  from_json j = Person {
    name: D.at "name" D.string j,
    age: D.at "age" D.int j,
    email: D.at "email" from_json j,
  }
}

main () = {
  let alice = Person { name: "Alice", age: 30, email: Just "a@example.com" }
  let json = E.serialize alice
  let back = D.deserialize json : Result Person J.Error
  dbg back
}

Missing fields and wrong shapes become InvalidShape errors. Invalid JSON syntax becomes InvalidJson.

The removed paths are intentionally absent: no deriving, no runtime Options, no SagaJson.Codec, and no Symbol-based reflected field names.