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dmmulroy / example-usage.ts
Last active January 13, 2026 14:30
Durable Object stub wrapper with better-result hydration
// example-usage.ts
import { Result } from "better-result";
import { stubWithBetterResultHydration } from "./stub-with-better-result-hydration";
import type { MyDurableObject } from "./my-durable-object";
// In a Worker handler:
export default {
async fetch(req: Request, env: Env) {
const id = env.MY_DO.idFromName("user-123");
import { DurableObjectError } from "./errors";
import { Err, Ok, Result, type Result as ResultType } from "./result";
/**
* Adds DurableObjectError to Result error unions, wraps non-Result returns.
* - Promise<Result<T, E>> → Promise<Result<T, E | DurableObjectError>>
* - Promise<T> → Promise<Result<T, DurableObjectError>>
*/
type AddDOError<R> =
R extends Promise<ResultType<infer T, infer E>>

Worker Bindings Architecture

1. How env.MY_D1 Works Under the Hood

Data Flow: Configuration → C++ → JavaScript

workerd.capnp config → server.c++ (parsing) → WorkerdApi::Global → createBindingValue() → v8::Object (env)
import { describe, expect, it } from "vitest";
import { AsyncResult, Result } from "./result";
describe("Ok", () => {
it("isOk returns true", () => {
expect(Result.ok(1).isOk()).toBe(true);
});
it("isErr returns false", () => {
expect(Result.ok(1).isErr()).toBe(false);
/**
* Mixin factory for discriminated error classes with typed props.
*
* Props become readonly fields; `message`/`cause` auto-wire to Error; `cause.stack` chains.
*
* @see [TypeScript Mixins](https://www.typescriptlang.org/docs/handbook/mixins.html)
* @typeParam Tag - Literal string for `_tag` discriminant
* @returns Base class to extend with optional generic props
*
* @example
import { describe, expect, it } from "vitest";
import { Result } from "./result";
describe("Ok", () => {
it("isOk returns true", () => {
expect(Result.ok(1).isOk()).toBe(true);
});
it("isErr returns false", () => {
expect(Result.ok(1).isErr()).toBe(false);
/**
* Utility functions for creating `PromiseSettledResult` instances.
*
* Provides methods to construct fulfilled and rejected promise results,
* ensuring they resolve asynchronously.
*/
const PromiseSettledResult = {
/**
* Creates a fulfilled `PromiseSettledResult`.
*
import { Effect, Layer, Stream } from "effect";
import { handleOntraportCreateContact } from "./handle-ontraport-create-contact";
import { handleProccesMetricsUpload } from "./handle-process-metrics-upload";
import { handleSendVerificationEmail } from "./handle-send-verification-email";
import { Message } from "./message";
import { Postgres } from "./postgres";
import { RetryPolicy } from "./retry-policy";
import { flatten } from "flat";
export type JobStatus = "new" | "locked" | "completed" | "error";