{"slug": "this-week-in-effect-137", "title": "This Week in Effect - 137", "summary": "Effect, the TypeScript library for building AI-era applications, shipped a runtime performance pass in issue 137 of its \"This Week in Effect\" newsletter, eliminating wasted work across Schema compilation, the core run loop, Queue, Stream, and Scope. The release also fixed concurrency bugs including Queue takers and offers parking forever after a yield, a lost wakeup during taker registration, and Layer.MemoMap hanging or leaking a shared layer when a requester is interrupted, and added APIs such as Config.flatMap, Schema.StringForLiteralAutocomplete, and isPubSub, isTxChunk, and isPlatformError type guards. On the AI provider side, Effect added support for raw JSON Schema dynamic tool calls, fixed Anthropic gateway 4xx error mapping, and retried OpenAI WebSocket turns after a previous_response_not_found error.", "body_md": "Hi Effecters!\n\nWelcome back to This Week in Effect, your weekly update of the latest developments in the Effect community and ecosystem.\n\nEffect is the TypeScript library for the AI era, helping 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.\n\nTo get started, below you’ll find links to our documentation and our guide for installing Effect. Enjoy!\n\n**Recent major updates:**\n\n## \n\nNew [Module of the Week](https://effect.website/blog/module-of-the-week/rcmap) post by [Maxwell Brown](https://x.com/maxwellbrown), featuring **RcMap**.\n\nBetter late than never - this week's Module of the Week is all about RcMap, [@EffectTS_](https://twitter.com/EffectTS_) 's reference counted map module.\nSee you nerds at Office Hours tomorrow!\n[effect.website/blog/module-of…](https://effect.website/blog/module-of-the-week/rcmap)\n\n### \n\nThis week brought a major runtime performance pass, with dozens of fixes eliminating wasted work across Schema compilation, the core run loop, Queue, Stream, and Scope, alongside several new APIs and continued RC hardening.\n\n- \n**Runtime performance pass** : Stopped the Effect run loop from building a success`Exit` between continuations, stopped`Queue` /`TxPriorityQueue` from doing unnecessary re-sorting and traversal work, stopped`MutableList` from retaining a slot for every element that ever passed through a never-emptying list, stopped forked`Scope` s from registering a finalizer just to leave their parent, and fixed`Stream.forever` /`Stream.repeat` slowing down and leaking memory on every repetition.\n- \n**Schema compilation performance** : Compiled recursive Schema equivalence once instead of once per value level, stopped Schema compilation re-analyzing every sub-schema for each enclosing schema, stopped rebuilding parser wrappers on every`SchemaParser.asserts` call, stopped compiled Schema structs retaining an unused parse traversal, and stopped a recursive Schema formatter holding one compiled body per level.\n- \n**Concurrency correctness fixes** : Fixed`Queue` takers and offers parking forever after a yield, fixed a lost wakeup during taker registration, fixed cleanup registration interruption gaps, fixed spans that never end when a traced region is interrupted as it starts, fixed`Layer.MemoMap` hanging or leaking a shared layer when a requester is interrupted, and made`awaitAllChildren` interruptible.\n- \n**New APIs** : Added`Config.flatMap` , added`Schema.StringForLiteralAutocomplete` , added family-aware`NetAddress` type helpers, added`isPubSub` ,`isTxChunk` , and`isPlatformError` type guards, and added dual forms to several existing APIs.\n- \n**Module reorganization** : Moved`Arbitrary` to the top-level module, moved several unstable Effect modules to top-level paths, split encoding formats into dedicated modules, and renamed the HTTP API module path.\n- \n**Cluster & workflow** : Fixed workflow execution ID collisions from ambiguous hash inputs, and bounded local entity registration waits.\n- \n**AI providers** : Added support for raw JSON Schema dynamic tool calls, fixed Anthropic gateway 4xx error mapping, retried OpenAI WebSocket turns after a`previous_response_not_found` error, and preserved streamed text and tool arguments for nullable delta role and tool call IDs.\n- \n**Bundle size** : Reduced`BigDecimal` bundle size, and built`Mime` lookup tables lazily on first use instead of eagerly.\n- \n**Documentation** : Clarified JSON Schema decoding with the canonical codec, and refreshed`PlatformError` migration guidance.\n\nYou can follow the full changelog in the [effect repository](https://github.com/Effect-TS/effect/commits/main).\n\nTo catch up on more updates, check out [Effect v4 Updates](https://www.effect.website/blog?category=effect-v4-updates), starting from the recently published [Effect v4 RC: August 2026 Updates](https://www.effect.website/blog/effect-v4-rc-august-recap).\n\nOther technical updates from the past week.\n\n### \n\n- [Fix Kysely result plugins with Effect SQL clients](https://github.com/Effect-TS/effect/pull/8262) (Bug Fix)\n- [Fix sql-pg pool cleanup after failed readiness probe](https://github.com/Effect-TS/effect/pull/8480) (Bug Fix)\n\n## \n\n- \nEffect NYC Meetup was a blast! Thanks to all the attendees, Zach Sherman, and Hyper for hosting us! The NYC [@EffectTS_](https://twitter.com/EffectTS_) community was out in force tonight!\nHuge shout out to[@zshrm](https://twitter.com/zshrm) and Hyper for hosting us in their amazing office!Had an awesome time with the rest of the Springbird team! Thanks for hosting an awesome event! The NYC @EffectTS_ community was out in force tonight! Huge shout out to @zshrm and Hyper for hosting us in their amazing office!\n- \nWe have one more Meetup in the US next week. Join us at [Effect San Francisco](https://luma.com/all-things-effect) on Sep 30 at CodeRabbit.\n- \nOnly a few 2-day passes left for [Effect Days 2026](https://effect.website/effect-days) ? The conference is scheduled for December 9–11 in Livorno, Italy.I’ll be speaking here about [@warpdotco](https://twitter.com/warpdotco) ’s effect journeyEffect Days is back 🇮🇹 Join us on December 9–11 for three days with the people building Effect and the people building with it. Workshops. Talks. Community. Early Bird tickets are now live ↓ effect.website/effect-days\n- \nEffect Office Hours 🔥 every Wednesday at 10:00 AM ET / 16:00 CET on our [YouTube channel](https://www.youtube.com/@effect-ts) .\n\nVisit our [Effect Community Events calendar](https://luma.com/effect-community) and subscribe for updates on upcoming Effect events.\n\n## \n\nWe’re thrilled to announce Ziverge as the first Effect Adoption Partner!\n\nHere are 3 things we're thrilled to announce, as part of our partnership with [@EffectfulTech](https://twitter.com/EffectfulTech), creators of [@EffectTS_](https://twitter.com/EffectTS_)  🔥 \n➡️ Ziverge will be sponsoring Effect Days\n➡️ We have produced an Effect SDK for [@GolemCloud](https://twitter.com/GolemCloud)\n➡️ We've launched an [@EffectTS_](https://twitter.com/EffectTS_) Training Workshop\nSign up for \n\n## \n\n- Okay, say no more, Matthew🤝\n\nI sort of feel like [@astrodotbuild](https://twitter.com/astrodotbuild) should do something to integrate with [@EffectTS_](https://twitter.com/EffectTS_) some how. I have no actual ideas here so don't ask me, it just feels *directionally* the right thing to do.\n\nI was in on [@EffectTS_](https://twitter.com/EffectTS_) two and a half years ago, receipts: [x.com/matthewcp/stat…](https://x.com/matthewcp/status/1783199977969193132)\n\nVery excited. I remember a number of years ago there were a number of attempts to do similar things in regular JavaScript that didn't catch on. I think TypeScript has made it much more viable. I think it's one of the most important libraries being developed today.\n\n- Can’t wait for the episode to come out!\n\nwe just recorded a [@NextTokenShow](https://twitter.com/NextTokenShow) episode where [@RhysSullivan](https://twitter.com/RhysSullivan) dives into how he’s using this exact stack! It’s so good\n\nin Executor v2, it's actually taking advantage of effect's error system now all of the error states will have clear error messages, along with that, for the ones that are fixable via your agent i.e apps using the wrong auth they will include a prompt to use\n\n- Anyone?\n\nanyone else wanna join me in pressuring [@benswerd](https://twitter.com/benswerd) to make an [@EffectTS_](https://twitter.com/EffectTS_) SDK for [@freestyle_dev](https://twitter.com/freestyle_dev)\n\n- Welcome, Fernando!\n\ni started using effect this week...and i think i'm really enjoying it\n\n- \n[Coach](https://www.masterclass.com/coach) by MasterClass - a real-time professional coaching app from MasterClass, built with Effect in both the Electron app and the backend.\n- \n[saas-starter](https://github.com/vantionlabs/saas-starter) - a production-ready multi-tenant B2B SaaS template built on Effect 4, React 19, TanStack Start, Postgres with row-level security, Redis, and Stripe, shipping with auth, billing, and tenant isolation already implemented. By Vantion Labs.\n- \n[Sweetener](https://sweetener-ts.github.io/) - hygienic, declarative macros for TypeScript. Try the[Effect do-notation macro](https://sweetener-ts.github.io/#/play/effect-do) in the playground.\n\n## \n\nDon’t forget to listen to our **Cause & Effect** podcast hosted by Johannes Schickling and available on [YouTube](https://www.youtube.com/@effect-ts), [X(Twitter)](https://x.com/EffectTS_/status/2085682364315783506), and audio platforms like [Spotify](https://open.spotify.com/episode/12L2neeIte6LUYQpzTh9n6) and [Apple Podcast](https://podcasts.apple.com/us/podcast/software-engineering-in-the-age-of-ai-10/id1781879869?i=1000780438320).\n\nJohn A. De Goes, the creator of [ZIO](https://zio.dev/), as well as CEO of [Ziverge](https://www.ziverge.com/) and [Golem Cloud](https://golem.cloud/), joins Johannes Schickling and Michael Arnaldi to discuss how AI is reshaping software engineering, what developers should still learn, and why Effect’s primitives are especially valuable for coding agents.\n\n[Play](https://youtube.com/watch?v=irmz5X3c7Do)\n\n## \n\n- Effect Office Hours 47 🔥\n\n[Play](https://youtube.com/watch?v=chLdsLqRs1E)\n\n- Effect-mq: Background jobs for Effect w/ Adam Rankin, Warp CTO.\n\n[Play](https://youtube.com/watch?v=rmChtqHB9jY)\n\n- PersistedQueue | Module of the Week #1 by Maxwell Brown.\n\n[Play](https://youtube.com/watch?v=Fzmdn4wWGpU)\n\n## \n\nLooking for a role where you can work with Effect? We now have a dedicated Effect jobs page featuring open roles from companies that use Effect. We’ll keep it updated as new opportunities come in.\n\n[Explore Effect job opportunities →](https://www.effect.website/effect-jobs)\n\n*Disclaimer: Please note that these job postings are shared for informational purposes, and we encourage applicants to verify details directly with the hiring companies.*\n\n## \n\nThe [Effect Merch Store](https://effect.website/merch) offers a selection of Effect-branded items designed for the community. All orders are processed and fully managed through [Printful](https://www.printful.com/).\n\nEffect Merch is here! \nWe’re excited to announce the launch of our Effect merch page! Grab your favorite swag & show your love for Effect in style! 🧢\n[effect.website/merch](https://effect.website/merch)\n\n## \n\nThat’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.\n\n*Effect Community Team*\n\n[Previous Module of the Week - RcMap](https://effect.website/blog/module-of-the-week/rcmap)", "url": "https://wpnews.pro/news/this-week-in-effect-137", "canonical_source": "https://effect.website/blog/this-week-in-effect/137/", "published_at": "2026-09-25 00:00:00+00:00", "updated_at": "2026-09-25 16:31:31.793390+00:00", "lang": "en", "topics": ["developer-tools", "ai-tools", "artificial-intelligence"], "entities": ["Effect", "Maxwell Brown", "RcMap", "Anthropic", "OpenAI", "Schema", "Queue", "Layer.MemoMap"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/this-week-in-effect-137", "markdown": "https://wpnews.pro/news/this-week-in-effect-137.md", "text": "https://wpnews.pro/news/this-week-in-effect-137.txt", "jsonld": "https://wpnews.pro/news/this-week-in-effect-137.jsonld"}}