# Effect-TS



The **`@dojocho/effect-ts`** dojo is a 40-kata curriculum for
[Effect-TS](https://effect.website). 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 [#install]

```sh
dojo setup
dojo add effect-ts
```

Then in your agent:

```
/kata
```

## What you'll learn [#what-youll-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 [#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 [#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 [#source]

The dojo source lives in the [Dojocho monorepo](https://github.com/tomsiwik/dojocho/tree/main/dojos/effect-ts).