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:
- We started publishing the talks from Effect Days 2025!
- The Effect community on Discord reached 4000+ members!
- Effect 3.14 has been released.
Technology
Maxwell Brown, Effect Core Contributor and Founding Engineer at Effectful Technologies, wrote about Developing AI Applications with Effect, showing how Effect’s AI integration packages simplify working with LLMs, enabling developers to build scalable, provider-agnostic AI applications with less complexity and greater flexibility.
Here are all the technical changes from this week.
Effect Core
- Add docs to effect/HashSet module (Documentation Update)
- Fix Data.TaggedEnum with generics regression (Bug Fix)
- Docs(effect/HashSet): fix HashSet.md api docs (Documentation Update)
- Allow Effect.fnUntraced to return non-effects (Bug Fix)
- Ensure Equal considers URL by value (Bug Fix)
- Add Stream.toAsyncIterableRuntime api (Feature, next-minor)
- Add docs to effect/MutableHashSet module (Documentation Update)
- Add Layer.setRandom, for over-riding the default Random service (Feature, next-minor)
- Fix JSONSchema generation for record values that include undefined (Bug Fix)
Effect AI
- Handle arbitrary length StreamChunkPart (Bug Fix)
- Add manual gpt-4.5-preview fix for CreateChatCompletionResponse schema (Bug Fix)
Effect Cluster
Effect Platform
- Pass options to HttpServerResponse.raw (Bug Fix)
- Fix(platform-node): Handle empty chunks in streams (Bug Fix)
- Allow removing multiple Headers (Feature, next-minor)
- Re-export default from Undici (Bug Fix)
Effect RPC
- Ensure RpcClient fiber is defined before polling (Bug Fix)
- Allow RpcGroup.merge to accept multiple groups (Feature)
- Remove trailing slash from rpc http requests (Bug Fix)
- Fix assignability in RpcGroup.merge (Bug Fix)
- Fix rpc README server example (Documentation Update)
Effect SQL
Community Highlights
We’re excited to share another community milestone: the Effect Discord reached 4k+ members!🚀
Another thrilling news from this week: Effect has been featured in the Thoughtworks Technology Radar Vol 32 in the Languages and Framework section, with the Thoughtworks team highlighting that after using Effect, their team found no reason to go back.
Marcelo Bairros shared a demo application showing how to run an Effect Cluster app with the SST Cluster component with a 1-command deploy. A great starting point if you want to see Effect Cluster in action.
Victor Korzunin built an interface for uploading large files (up to 5 TiB) for developers working with Effect and AWS S3 service.
Dillon Mulroy live-streamed four episodes of his series Freelance project with TypeScript, Svelte 5, and EffectTS 🚀 on his Twitch channel.
Effect Days 2025 Updates
We’ve published the first two talks from Effect Days 2025:
Opening remarks by Johannes Schickling, DX at Effect. Johannes shared updates on Effect’s advancements over the past year and key improvements like documentation, Effect AI, and the Effect Playground. He emphasized how Effect continues to simplify the complexities of building production-grade systems, especially in the AI space.
Building Effect-ive Agents, keynote by Maxwell Brown. Maxwell talked about complex agentic systems using Effect and Effect’s AI integration packages, emphasizing a practical approach with code examples. He showcased how developers can leverage Effect to build scalable, resilient, and maintainable systems for working with large language models (LLMs).
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 published 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:
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 Effect 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
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