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 of the key features 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.

Get started with Effect with our quick-start guide and documentation below:

• Effect quick-start guide
• Effect docs

Recent major updates:

• Effect is API stable with the Effect 3.0 release.
• Effect 3.9 has been released.
• The Effect community on Discord reached 3640+ members!

#Technology

• Effect 3.9 has been released!

Here are all the technical changes from this week (note that changes included in the 3.9 release will not be listed)

#Effect Core

• Improve DX of type errors from inside pipe and flow (Improvement)
• Ensure random numbers are correctly distributed (Bug Fix)
• Revert deno support to Inspectable (Bug Fix)
• Allow tacit usage with do notation apis (.bind / .let) (Improvement)
• Add TSubscriptionRef (Feature, next-minor)

#Effect Experimental

+Add ai packages (Feature)

#Effect Opentelemetry

• Add Tracer.withSpanContext (Feature)

#Effect Platform

• Fix: handle blob message data from websocket (Bug Fix)
• Add HttpClientResponse.filterStatus apis (Feature)
• Revert deno support to Inspectable (Bug Fix)
• Platform: add documentation on Scope requirement for HTTP requests (Documentation Update)
• HttpClient refactor & simplification (Refactor)
• Update HttpClient accessor changeset (Refactor)
• Add dotenv support to PlatformConfigProvider (Feature)
• Add support for WebSocket protocols option (Feature)

#Effect RPC

• Feat: add support for spanPrefix to HttpRpcRouter (Feature)

#Effect Schema

• Revert deno support to Inspectable (Bug Fix)
• Enhanced Error Reporting for Discriminated Union Tuple Schemas (Enhancement)
• Allow Schema.Either to support Never without type errors (Bug Fix)

#Effect SQL

• Test sql connection as part of client construction (Improvement)
• Fix Transactions in sql-libsql (Bug Fix)
• @effect/sql-libsql allow either a pre-built client or configuration options (Feature)

#Effect Typeclass

• Allow tacit usage with do notation apis (.bind / .let) (Improvement)

#Effect Vitest

• Test sql connection as part of client construction (Improvement)

#General Chores

• Increase timeout for release action

#Community highlights

• This week we celebrate another community milestone: Effect reached 1.2 million weekly downloads through npm!

• Effect Days 2025 Tickets are now on sale! As announced in the last TWIE, Effect Days will be taking place on March 19-21, 2025 at Palazzo Pancaldi in the Tuscan Italian town, Livorno.

• New speaker announcement for the Effect Meetup in San Francisco. Our third speaker will be David Siegel, Founder & CEO of Glide.

• Dillon Mulroy, Software Engineer at Vercel, livestreamed two new episodes about Building with EffectTS, Svelte 5, and Postgres on his Twitch channel.

#Effect content updates

• Maxwell Brown & Michael Arnaldi went live on X and Twitch on Tuesday with a special educational session about Software Transactional Memory in Effect. The video will soon be available on our YouTube.

• Mattia Manzati started a new series on Twitch about Building a small warehouse app with Effect.

• The special episode Effect Cluster Development - Re-Thinking the Entity Manager by Maxwell Brown has already been published on the Effect YouTube Channel.

#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