Effect-TS

Master Effect-TS through 40 hands-on katas, from Effect.succeed to managed runtimes.

The @dojocho/effect-ts dojo is a 40-kata curriculum for Effect-TS. You build up from the smallest unit (Effect.succeed) all the way to layered services, fibers, streams, and a managed runtime — one failing test at a time.

Install

dojo setup
dojo add effect-ts

Then in your agent:

/kata

What you'll learn

The dojo is organised into areas. Each area starts with a skill the sensei loads before the first kata, then walks through the APIs hands-on:

Area	Katas	Topics
Foundations	001 – 005	`Effect.succeed`, `map`, generators, `flatMap`, `pipe` composition
Errors	006 – 008	`Effect.fail`, tagged errors, error channels, recovery patterns
Modelling	009 – 010	`Option`, `Either`, `Exit`
Services & Layers	011 – 013	`Context.Tag`, `Layer`, testing with mocks
Schema	014 – 015	`Schema.Struct`, refinements, domain modelling
Concurrency	016 – 020	`retry`, schedules, parallelism, `race`, `Ref`, fibers
Resources	021 – 023	`acquireRelease`, scoped layers, resource patterns
Streams	024 – 027	`Stream` basics, operations, combinators, data pipelines
Observability	028	logging, spans
HTTP	029	typed HTTP client
Capstone	030	end-to-end, all areas combined
Advanced	031 – 040	config, causes, pattern matching, queues, metrics, managed runtime, request batching

Each kata is a single failing Vitest test. Your sensei reads the test and the SENSEI.md, then asks you targeted questions until you make it green.

Teaching contract

Quoting the dojo's own DOJO.md:

Never give solutions. Your role is Socratic guide.

Ask questions that steer toward the answer

Point to type signatures or API names

Narrow scope: "Focus on the first failing test"

Never write or show solution code

That contract is enforced kata-by-kata via per-kata SENSEI.md files, which also flag which APIs belong to you (the student) versus the test harness (runSync, runSyncExit) — a small but important detail Effect-TS beginners often get backwards.

Requirements

Node.js 20+
A package manager that supports workspaces — pnpm is recommended.
The effect runtime is installed as a dependency of the dojo; the test runner is Vitest.

Source

The dojo source lives in the Dojocho monorepo.