Hi Effecters!
Welcome back to This Week In Effect (TWIE) - your weekly update of the latest developments in the Effect community and ecosystem.
Effect is a powerful TypeScript library that helps developers build complex, synchronous, and asynchronous programs. One key feature that sets Effect apart is how it leverages structured concurrency to provide features such as async cancellation and safe resource management, making it easier to build robust, scalable, and efficient programs.
To get started, below you’ll find links to our documentation and our guide for installing Effect. Enjoy!
Recent major updates:
@effect/workflow - currently in alpha.
A landmark week for the v4 beta — the effect-smol repository was archived and its full Git history merged into the canonical Effect-TS/effect repository. The main branch of Effect-TS/effect is now officially Effect v4. Here are the most notable changes that landed this week.
Repository milestone: Effect v4 has moved to the canonical Effect-TS/effect repository. The main branch is now v4, while v3 lives on the v3 branch. The effect-smol repo is archived and read-only, with all history preserved for reference.
Graph module: Added graph set operators (union, intersection, difference), made Graph interfaces opaque for better encapsulation, fixed edge transforms, mutation finalization, Walker iterator receiver, toGraphViz DOT escaping, floydWarshall null edge costs, isAcyclic for parallel undirected edges, and isGraph predicate narrowing. Also documented graph set operation gotchas.
CLI: Reintroduced CLI wizard mode, added CLI config for built-in flags, fixed missing flag value handling, fixed Command.withSubcommands losing context type inference, and added general cleanups.
HttpApi hardening: Reused response schemas, normalized payload media types, hardened HTML rendering in API docs, fixed client error and authorization decoding, improved type-level performance, kept HttpApi composition immutable, applied transformClient when building individual endpoint clients, rejected duplicate and unknown handler registrations with descriptive errors, rejected duplicate OpenAPI operations and incompatible security scheme names, compiled SSE client decoders once instead of per-request, preserved __proto__ identifiers, and added HttpApiError for status 422.
Durable execution: Fixed durable race result replay, ensured PersistedQueue decoding failures count as processing attempts, fixed Redis-backed PersistedQueue script handling, and fixed SQL-backed persisted queues to refresh locks for actively acquired elements.
Schema fixes: Fixed JSON Schema tuple allOf intersections, fixed tuple post-rest element indexing, fixed union candidate dispatch ordering, and prevented prototype pollution in bracket-path decoding.
AI: Fixed provider-defined tools (tool cloning and Anthropic client tools), and removed the legacy LSP in favor of effect/tsgo.
Runtime: Fixed handling of large millisecond values passed to sleep.
To catch up on more updates, check out Effect v4 Beta updates.
Other technical changes from the past week.
Thank you to all the attendees, speakers, and organizers of the Effect Miami 🇺🇸 #2 Meetup this week! 🙌
It was an amazing evening at @thelabmiami for @EffectTS_ Miami #2. Huge thanks to @DavidKPiano for coming all the way to Miami and sharing his latest work on @statelyai. @cbnsndwch gave a practical look at moving from NestJS to Effect, and @ariazou talked about typed,
Effect Utrecht 🇳🇱 is scheduled on July 23rd!
Less than 10 days to the event. Sign up at luma.com/gr9wtmgs @StefvanWijchen will tell us about weft github.com/stefvw93/weft a reactive DOM library where every node is an Effect More coming up soon!
I'm hosting an @EffectTS_ community gathering in Utrecht! Interested in an introduction to Effect? Networking with early adopters? Just interested in checking the vibes of the community? Join us on 23rd of July! luma.com/gr9wtmgs
Visit our Effect Community Events calendar and subscribe for updates on upcoming Effect events.
Skills by Kit Langton, including one for writing production TypeScript with Effect v4.
I threw my local @EffectTS_ skill up on github in case it's useful to anyone. github.com/kitlangton/ski…
Hype 👀
By the way, I get the @EffectTS_ hype now. What a great way of building software!
Addressing OpenAI
Post train on EffectTS please it will make models so much better at outputting good code
Some people use Mythos for security research, we use Tim Smart — cit Michael Arnaldi.
slack connect allows us to efficiently collaborate cross functionally with the best teams across the industry
💯
We are also doing this, but with @EffectTS_
x.com/i/article/2077…
Effect has the interesting effect (!) of making you like TypeScript and React again.
@EffectTS_ has the interesting effect (!) of making unlikable technologies likeable again. TS without Effect: Ugly - haphazard try/catch, combining random libraries, unprincipled abstractions. Add Effect: Typed errors, unified primitives replacing random libraries, elegant
This week, we started an ever-growing thread on 𝕏 collecting community-created Effect videos, from talks and tutorials to demos, podcasts, and workshops.
A running thread of Effect community videos 🧵 Talks, tutorials, demos, podcasts, workshops - in no particular order - we’ll collect useful videos from people across the community building with, teaching, and talking about Effect.
Crosshatch – an Effect-native toolkit for composing x402 payments, enabling accountless payments across EVM and Solana with USD-denominated stablecoins. By Harry Solovay.
Effect-native x402. Schemas, chain-agnostic adapter system, fetch/http layers, extension support and more coming soon! Please try it out and join the Discord! crosshatch.dev
yield* to handle async operations and side effects. Just hit its v4 release.
Don’t forget to listen to our Cause & Effect podcast hosted by Johannes Schickling and available on YouTube, X(Twitter), and audio platforms like Spotify and Apple Podcast.
Kit Langton joined the podcast to talk about Effect, OpenCode, and what it takes to migrate a large TypeScript codebase to Effect. Enjoy a very Kit episode, technical, funny, opinionated, and full of love for effect systems.
More and more companies are adopting Effect in their projects. Here’s a list of companies looking for software engineers with Effect experience:
Expand.ai: Founding Engineer
Freckle.io is hiring Full-stack Engineers with experience in Effect.
HumanLayer: Founding Product Engineer
Joymore is looking for Backend (and Full Stack) Engineers. See the job posting in the #job-board channel on our Discord.
LEAP Legal Software is hiring a Full-stack Engineer. See the job posting in the #job-board channel on our Discord, and reach out to Willem.
ManageSpace: Full Stack Engineer (mid-level) — UK/US/Europe. See the job posting in the #job-board channel on our Discord, and reach out to Adam.
PhosPhor is hiring engineers experienced in Effect. You may also reach out to the Phosphor team on our Discord.
Reap, a HK-based but remote-friendly Fintech company, is hiring a Backend/Cloud Engineer for a greenfield project. See the job posting in the #job-board channel on our Discord.
Sellhub is looking for a Backend Engineer. See the job posting in the #job-board channel on our Discord.
SynTwin hiring a Product Engineer.
Software Intelligence Works: Senior Full-Stack Engineer
Solid is hiring its early engineering team (Bay Area). The job posting is available in the #job-board channel on our Discord
Supermemory: Founding Backend / Infrastructure Engineer
Superwall: Full-stack Mobile Developer
Temper: Founding Engineer
Tranched: Full-stack Engineer Web3
Disclaimer: Please note that these job postings are shared for informational purposes, and we encourage applicants to verify details directly with the hiring companies.
The Effect Merch Store offers a selection of Effect-branded items designed for the community. All orders are processed and fully managed through Printful.
Effect Merch is here! We’re excited to announce the launch of our Effect merch page! Grab your favorite swag & show your love for Effect in style! 🧢 effect.website/merch
That’s all for this week. Thank you for being a vital part of our community. Your feedback is highly valued as we fine-tune this format. Feel free to share your thoughts, and we’ll do our best to tailor it to the needs of our community.
Effect Community Team