effect

Effect 4.0 is a ground-up rebuild of the TypeScript effect library, delivering a 5× smaller bundle, 6.4× higher concurrency throughput, 86% less memory per fiber, and zero runtime dependencies in the core package, alongside a new long-term support policy for every major version.

Matt Pocock praises the Effect library for agent development, highlighting typed errors and dependencies, dependency injection, and built-in abstractions that fit AI-agent coding in TypeScript. The post quotes the announcement of Effect v4, positioned as a foundation for building reliable software and AI agents in TypeScript.