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!
Recent major updates:
- The Effect Days conference is returning this March 2025! 🎉
- The Effect community on Discord reached 3850+ members!
- Effect 3.13 has been released.
Technology
Here are all the technical changes from this week.
Effect Core
- Schema: Export MakeOptions (Bug Fix)
- Match.tag + Match.withReturnType can use literals without as const (Improvement)
- Preserve branded primitive types in DeepMutable transformation (Bug Fix)
- Schema: add support for Transformation + Struct in extend (Bug Fix)
- Arbitrary: make called on Schema.Class now respects property annotations (Bug Fix)
- Disallow excess properties for various function options (Bug Fix)
- ConfigProvider: fromEnv: add missing Partial modifier (Bug Fix)
- Add additionalPropertiesStrategy option to OpenApi.fromApi (Improvement)
Effect AI
- Allow defects to pass through checks in AiPlan (Bug Fix)
- Ensure AiPlan builder returns the correct shape (Bug Fix)
- Avoid inclusion of _tag in tool call parameters (Bug Fix)
Effect Platform
- Fix w3c traceparent header parsing (Bug Fix)
- Disallow excess properties for various function options (Bug Fix)
- Fetch http client merge headers (Bug Fix)
- Bug fix: change interruptible order in platform shutdown flow (Bug Fix)
- Add additionalPropertiesStrategy option to OpenApi.fromApi (Improvement)
- Update platform README to link runMain docs to website (Documentation Update)
- Refactor NodeStream.toReadable (Refactor)
- Add additional properties options to HttpApiBuilder.middlewareOpenApi (Features)
- Ensure empty Chunk’s don’t cause NodeStream.toReadable to hang (Bug Fix)
- Expose ParseError in HttpApiClient (Improvement)
Effect Printer
- Update README.md (Documentation Update)
Effect Typeclass
General Chores
Community highlights
Attila Večerek, Senior Staff Engineer at Zendesk and speaker at the Effect Days 2025, launched a new blog series on Effective Pragmatism exploring the topic of software quality.
Michael Fester, founder of Markprompt, wrote about how they leverage Effect Schema and OpenAPI to create beautiful, interactive API documentation with zero maintenance overhead.
Inalegwu Ikwue developed Comic-Pulse, a simple app to keep people informed about their favorite comic books releases. The app uses Effect in the backend.
Milad Vafaeifard created effect-llm-test, a simple Todo app service with Effect and the LLM.txt provided.
Dillon Mulroy live-streamed four episodes of his series Freelance project with TypeScript, Svelte 5, 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! Get your ticket! 🎟️
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.
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, including the learning process, challenges faced, and benefits of integrating Effect into their tech stack.
We’re excited to present our second episode with Michael Fester from Markprompt about scaling AI-powered customer support with Effect, building reliable and high-performance infrastructure, and enhancing developer productivity in a fast-evolving AI landscape. 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 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-boardchannel 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