digitake/bs-promise-monad

Monadic syntax to work with promise in ReasonML

bs-promise-monad's Issues

Returning errors

Can't seem to understand what this wants me to return;

type idTokenT = {
  idToken,
} and idToken = {jwtToken: string};

let decodeJwt = json => Json.Decode.{jwtToken: json |> field("jwtToken",string)}
let decodeToken = json => Json.Decode.{
  idToken: json |> field("idToken", decodeJwt),
};

type auth;
[@bs.module "@aws-amplify/auth/lib"] external auth: auth = "default";
[@bs.send] external getCurrentSession:(auth,unit)=> Js.Promise.t(Js.Json.t) = "currentSession";

let getJwtToken = () => {
    open PromiseMonad;
    getCurrentSession(auth,())
    >>= (response => {
        let jwtToken = decodeToken(response);
    Js.log(jwtToken);
    return(jwtToken);
  })
>>| (err => {
    let errMsg = err |> Js.Json.stringifyAny |> Js.Option.getWithDefault("");
    Js.log2("Failure!!", err);
    return(errMsg))
  });
};

This is the compiler error:

This has type:
    Js.Promise.t(Js.Promise.error) (defined as
      Js.Promise.t(Js.Promise.error))
  But somewhere wanted:
    Js.Promise.t(idTokenT) (defined as Js.Promise.t(idTokenT))

  The incompatible parts:
    Js.Promise.error (defined as Js.Promise.error)
    vs
    idTokenT

Any guidance would be appreciated. Thank you, sir.

Add auto-return for catch as well

Hi! Digging this stuff, makes it so much cleaner. I've added the following to mine just now:

let (>>/) = (m: Js.Promise.t('a), f: Js.Promise.error => 'a) => Js.Promise.catch(e => return(f(e)), m);

I would have made a PR, but the console is spewing errors at me when I try to compile and I'm not that familiar with Reason just yet :P