Decode into a union type?

[ben-eb]

Hello 👋

I'd like to use this library to decode some environment variables into a union type, something like this:

type SandboxEnviroment = {
  status: "sandbox";
  name: string;
}

type LiveEnvironment = {
  status: "live";
  name: string;
  credentials: string;
}

type Environment = SandboxEnviroment | LiveEnvironment

If I have IS_SANDBOX set to true in my environment, then I know that I don't need to read the SECRET_CREDENTIALS. But I know that when it's false then it's a production application that requires that secret to be defined.

If I were writing this in Elm then I'd want to read the IS_SANDBOX first, work out its value and then use that to pick which decoder I need to use, using andThen - https://package.elm-lang.org/packages/elm/json/latest/Json-Decode#andThen. I could also use succeed to produce the status on the type - https://package.elm-lang.org/packages/elm/json/latest/Json-Decode#succeed.

As far as I can tell, the library doesn't support this at the moment. Do you have any plans to add this?

Thanks!

[ben-eb]

I've since migrated my project to https://github.com/colinhacks/zod, so I don't need a fix for this. 👍