Using `effect` with `postgres`

import { Effect, Context } from "effect";
import postgres from "postgres";

const dbConn = postgres("postgres://postgres:postgres@localhost:5432/demo");

const IDbConn = Context.Tag<postgres.Sql>();

async function createUserInDb(conn: postgres.Sql) {
  // could throw an error if a constraint is violated
  await conn`INSERT INTO users (name) VALUES ('John')`

  return "user created"
}

async function createUserProfileInDb(conn: postgres.Sql) {
  // could throw an error if the user does not exist or some other constraint is violated
  await conn`INSERT INTO user_profiles (user_id, bio) VALUES (1, 'I am John')`

  return "user profile created"
}

function createUser() {
  return IDbConn.pipe(
    Effect.tryMapPromise({
      try: async (conn) => await createUserInDb(conn),
      catch: (error) => {
        if (error instanceof Error) {
          return error;
        }

        return new Error(`unknown error: ${error}`);
      },
    })
  )
}

function createUserProfile() {
  return IDbConn.pipe(
    Effect.tryMapPromise({
      try: async (conn) => await createUserProfileInDb(conn),
      catch: (error) => {
        if (error instanceof Error) {
          return error;
        }

        return new Error(`unknown error: ${error}`);
      },
    })
  )
}

async function withoutTransaction() {
  return Effect.gen(function* (_) {    
    const user = yield* _(createUser());
    const userProfile = yield* _(createUserProfile());

    return { user, userProfile };
  }).pipe(
    Effect.provideService(IDbConn, dbConn),
    Effect.runPromise,
  );
}

async function withTransaction() {
  // how to use effects with `postgres` transactions
  
  return Effect.gen(function* (_) {    
    const conn = yield* _(IDbConn);

    return conn.begin(async (sql) => {
      const user = yield* _(createUser());
      const userProfile = yield* _(createUserProfile());
      return { user, userProfile };
    });
  }).pipe(
    Effect.provideService(IDbConn, dbConn),
    Effect.runPromise,
  );
}