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 create 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 as well as our guide for installing Effect. Enjoy!

• Effect Documentation
• Installing Effect

Recent major updates:

• The Effect Days conference is returning this March 2025! 🎉
• The Effect community on Discord reached 3830+ members!
• Effect 3.13 has been released.

Technology

Here are all the technical changes from this week.

Effect Core

• Fix Duration.unsafeFormatIso docs (Documentation Update)
• Fix DateTime utc tests (Bug Fix)
• Add support for Schema.Enums in HttpApiBuilder.isSingleStringType (Feature)
• Remove duplicate code in stm (Bug Fix)
• Fix Context.Tag unification (Bug Fix)
• Switch from @effect/dtslint to tstyche for type-level testing (Refactor)
• Mark Option.filterMap as an alias of flatMap (Improvements)
• Chore: add missing type assertions (Optimization)
• Make runtime run sync dual (Feature, next-minor)
• Add Either.transposeOption (Feature, next-minor)
• Feat: add Array.window (Feature, next-minor)
• Fix nested batching (Bug Fix)
• Chore: add references for type test projects (Optimization)
• Schema: more precise return types when transformations are involved (Refactor)

Effect AI

• Add initial anthropic ai provider integration package (Feature)

Effect Platform

• Ensure key for header security is lower case (Bug Fix)
• Chore: add references for type test projects (Optimization)

Effect Typeclass

• Chore: add references for type test projects (Optimization)

Effect Vitest

• Deps: update vitest to v3 (Refactor)
• Fix vitest v3 deprecation warnings (Bug Fix)
• Suppress warning for experimental features (Bug Fix)

General Chores

• Fix jsdoc codemod
• Update pnpm and node version
• Fix import statement

Community highlights

• Ethan Niser wrote ‘The truth about Effect’, where he explains why, in his view, Effect is not just a TypeScript library, but a language for effectful computations with powerful features like typed errors, structured concurrency, fiber-based runtime, and more.

• Sandro Maglione published a guide about How to implement a backend setup with Effect – the repository is open source.

• Adam Engebretson released a new Effect wrapper for Raycast Extensions.

• Matt Rossman published a new guide about Getting started with tracing in Effect.

• Dillon Mulroy live-streamed an episode of his series Building a budget syncing app for Splitwise and YNAB with AI and EffectTS 🚀 on his Twitch channel.

Effect Days 2025

The Effect Days conference is happening on March 19-21, 2025, and it’s the perfect chance to connect with the Effect community and celebrate the Effect ecosystem in person!

The workshop at Effect Days is officially SOLD OUT! 🎉 A huge thank you to everyone who grabbed a spot! If you missed out, don’t worry—there are still tickets available for the main conference! 🎟️ Get yours now:effect.website/events/effect-…

This week, we announced Mattia Manzati and Elliot Dauber as conference speakers.

• Mattia Manzati is an Effect Cluster contributor and will share the dev-tools available to Effect developers – and what’s coming next.

• Elliot Dauber is a Founding Engineer at Markprompt and will share his experience about building LLM applications at scale with Effect.

(https://twitter.com/EffectTS_/status/1892531342484586596)

Shout out to our conference sponsors, Inato and Evryg.

Inato is a global clinical trial marketplace that brings research to patients where they live. The Inato team is a long-time supporter of Effect and actively advocates for it within the developer community.

Effect content update

• Maxwell Brown and Tim Smart were live on X(Twitter) and Twitch on Tuesday with a new episode of Reimagining ContentLayer with Effect.

Re-Imagining Contentlayer with Effect x.com/i/broadcasts/1…

The twelfth and the thirteenth episodes of Re-building Contentlayer with Effect have been published on the Effect YouTube Channel.

Cause & Effect Podcast

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. This podcast highlights stories from software engineers and companies using Effect in production. Each episode explores their journey of adopting Effect, the learning process, the challenges faced, and the benefits of integrating Effect into their tech stack.

In our first episode, we were joined by Attila Večerek, Tech Lead & Staff Engineer, who discussed how Zendesk incrementally adopted Effect in a polyglot environment with a large codebase. Give it a listen and let us know what you think on our social media or Discord!

Effect Merch Store

In December 2024, we unveiled the Effect Merch Store, with a selection of Effect-branded items designed for the community. All orders are processed 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

Effect job opportunities

More and more companies are adopting Effect in their projects — here’s a list of companies looking for software engineers with Effect experience:

• Superwall : Full-stack TS developer with backend & infrastructure experience.

• Expand.ai : Founding Engineer

• Platonic Systems : Remote Effect Engineers

• Inato : Senior Product Engineer

• Medbill.ai : Founding Software Engineers (full-stack and backend)

• Oneiro Solutions : Software Engineer - Core Team. Join our Discord and DM leighman for further info.

• Microsub : TS Developer

• Samsung Food : Full Stack Developer

• Stealth team looking for an Engineer with experience in Effect. The job posting is available in the #job-board channel on our Discord.

Disclaimer: Please note that these job postings are shared for informational purposes, and we encourage applicants to verify details directly with the hiring companies.

Closing notes

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