effect-ts

Name: effect-ts
Author: joelhooks

77installs1forks

How to install effect-ts?

joelhooks/effectts-skills/effect-ts

$npx -y skills add joelhooks/effectts-skills --skill effect-ts

Installs into the current project.

Summary

Write idiomatic Effect v4 TypeScript following official best practices from effect-solutions and the Effect source. Use when writing, reviewing, or refactoring Effect code: services (ServiceMap.Service), layers and dependency injection, error handling (Schema.TaggedErrorClass), d

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SKILL.md

1	# Effect-TS (v4)
2
3	Patterns from [effect-solutions](https://effect.solutions) and the [Effect source](https://github.com/effect-ts/effect). This covers the latest v4 APIs.
4
5	## Source-First Rule
6
7	When working in any repo that uses Effect (`effect` or `@effect/*` in package/dependency files), reference the official Effect source before writing, reviewing, or refactoring Effect code. Do not rely on stale memory, blog posts, or high-level docs alone.
8
9	- If the `effect_source` tool is available, use it for `status`, `hydrate`, and `search` instead of hand-rolled shell commands.
10	- First check for a repo-local shallow source mirror at `.agent-sources/effect/`.
11	- If it is missing, create it before doing Effect work:
12	`mkdir -p .agent-sources && git clone --depth 1 --filter=blob:none https://github.com/effect-ts/effect.git .agent-sources/effect`
13	- Keep the mirror out of product commits. If needed, add `.agent-sources/` to `.git/info/exclude`, not the project `.gitignore`, unless Joel explicitly wants it committed.
14	- Search the mirror for current patterns and APIs, especially under `packages/effect/src/` and package tests/examples, before calling something an Effect best practice.
15
16	## Local Source References
17
18	- repo-local Effect source mirror (canonical for current work): `.agent-sources/effect/`
19	- effect-solutions (best practices, docs, examples): `~/Code/kitlangton/effect-solutions/`
20	- fallback global Effect monorepo: `~/Code/effect-ts/effect/`
21	- Search source for implementations: `grep -r "pattern" .agent-sources/effect/packages/effect/src/`
22
23	## Effect.gen and Effect.fn
24
25	`Effect.gen` provides sequential, readable composition (like async/await for Effect):
26
27	```typescript
28	import { Effect } from "effect"
29
30	const program = Effect.gen(function* () {
31	const data = yield* fetchData
32	yield* Effect.logInfo(`Processing: ${data}`)
33	return yield* processData(data)
34	})
35	```
36
37	`Effect.fn` adds call-site tracing and named spans. Use for all service methods:
38
39	```typescript
40	const processUser = Effect.fn("processUser")(function* (userId: string) {
41	yield* Effect.logInfo(`Processing user ${userId}`)
42	const user = yield* getUser(userId)
43	return yield* processData(user)
44	})
45
46	// Second argument for cross-cutting concerns (retry, timeout)
47	const fetchWithRetry = Effect.fn("fetchWithRetry")(
48	function* (url: string) {
49	const data = yield* fetchData(url)
50	return yield* processData(data)
51	},
52	flow(
53	Effect.retry(Schedule.recurs(3)),
54	Effect.timeout("5 seconds")
55	)
56	)
57	```
58
59	## ServiceMap.Service
60
61	Define services as classes with a unique tag and typed interface:
62
63	```typescript
64	import { Effect, ServiceMap } from "effect"
65
66	class Database extends ServiceMap.Service<
67	Database,
68	{
69	readonly query: (sql: string) => Effect.Effect<unknown[]>
70	readonly execute: (sql: string) => Effect.Effect<void>
71	}
72	>()("@app/Database") {}
73	```
74
75	Implement with `Layer.effect` or `Layer.sync`, using `Effect.fn` for all methods:
76
77	```typescript
78	import { Effect, Layer } from "effect"
79
80	class Users extends ServiceMap.Service<
81	Users,
82	{
83	readonly findById: (id: UserId) => Effect.Effect<User, UserNotFoundError>
84	readonly all: () => Effect.Effect<readonly User[]>
85	}
86	>()("@app/Users") {
87	static readonly layer = Layer.effect(
88	Users,
89	Effect.gen(function* () {
90	const http = yield* HttpClient.HttpClient
91	const findById = Effect.fn("Users.findById")(function* (id: UserId) {
92	const response = yield* http.get(`/users/${id}`)
93	return yield* HttpClientResponse.schemaBodyJson(User)(response)
94	})
95	const all = Effect.fn("Users.all")(function* () {
96	const response = yield* http.get("/users")
97	return yield* HttpClientResponse.schemaBodyJson(Schema.Array(User))(response)
98	})
99	return { findById, all }
100	})
101	)
102	}
103	```
104
105	Rules:
106	- Tag identifiers must be unique. Use `@app/ServiceName` pattern
107	- Service methods should have `R = never` (dependencies via Layer, not method signatures)
108	- Use `readonly` properties
109
110	See [references/services-and-layers.md](references/services-and-layers.md) for service-driven development, test layers, layer memoization, and full composition patterns.
111
112	## Schema.Class and Branded Types
113
114	Use `Schema.Class` for domain records. Brand all entity IDs and domain primitives:
115
116	```typescript
117	impo

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effect-ts

77installs1forks

View on GitHub

How to install effect-ts?

joelhooks/effectts-skills/effect-ts

$npx -y skills add joelhooks/effectts-skills --skill effect-ts

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Effect-TS (v4)
2
3	Patterns from [effect-solutions](https://effect.solutions) and the [Effect source](https://github.com/effect-ts/effect). This covers the latest v4 APIs.
4
5	## Source-First Rule
6
7	When working in any repo that uses Effect (`effect` or `@effect/*` in package/dependency files), reference the official Effect source before writing, reviewing, or refactoring Effect code. Do not rely on stale memory, blog posts, or high-level docs alone.
8
9	- If the `effect_source` tool is available, use it for `status`, `hydrate`, and `search` instead of hand-rolled shell commands.
10	- First check for a repo-local shallow source mirror at `.agent-sources/effect/`.
11	- If it is missing, create it before doing Effect work:
12	`mkdir -p .agent-sources && git clone --depth 1 --filter=blob:none https://github.com/effect-ts/effect.git .agent-sources/effect`
13	- Keep the mirror out of product commits. If needed, add `.agent-sources/` to `.git/info/exclude`, not the project `.gitignore`, unless Joel explicitly wants it committed.
14	- Search the mirror for current patterns and APIs, especially under `packages/effect/src/` and package tests/examples, before calling something an Effect best practice.
15
16	## Local Source References
17
18	- repo-local Effect source mirror (canonical for current work): `.agent-sources/effect/`
19	- effect-solutions (best practices, docs, examples): `~/Code/kitlangton/effect-solutions/`
20	- fallback global Effect monorepo: `~/Code/effect-ts/effect/`
21	- Search source for implementations: `grep -r "pattern" .agent-sources/effect/packages/effect/src/`
22
23	## Effect.gen and Effect.fn
24
25	`Effect.gen` provides sequential, readable composition (like async/await for Effect):
26
27	```typescript
28	import { Effect } from "effect"
29
30	const program = Effect.gen(function* () {
31	const data = yield* fetchData
32	yield* Effect.logInfo(`Processing: ${data}`)
33	return yield* processData(data)
34	})
35	```
36
37	`Effect.fn` adds call-site tracing and named spans. Use for all service methods:
38
39	```typescript
40	const processUser = Effect.fn("processUser")(function* (userId: string) {
41	yield* Effect.logInfo(`Processing user ${userId}`)
42	const user = yield* getUser(userId)
43	return yield* processData(user)
44	})
45
46	// Second argument for cross-cutting concerns (retry, timeout)
47	const fetchWithRetry = Effect.fn("fetchWithRetry")(
48	function* (url: string) {
49	const data = yield* fetchData(url)
50	return yield* processData(data)
51	},
52	flow(
53	Effect.retry(Schedule.recurs(3)),
54	Effect.timeout("5 seconds")
55	)
56	)
57	```
58
59	## ServiceMap.Service
60
61	Define services as classes with a unique tag and typed interface:
62
63	```typescript
64	import { Effect, ServiceMap } from "effect"
65
66	class Database extends ServiceMap.Service<
67	Database,
68	{
69	readonly query: (sql: string) => Effect.Effect<unknown[]>
70	readonly execute: (sql: string) => Effect.Effect<void>
71	}
72	>()("@app/Database") {}
73	```
74
75	Implement with `Layer.effect` or `Layer.sync`, using `Effect.fn` for all methods:
76
77	```typescript
78	import { Effect, Layer } from "effect"
79
80	class Users extends ServiceMap.Service<
81	Users,
82	{
83	readonly findById: (id: UserId) => Effect.Effect<User, UserNotFoundError>
84	readonly all: () => Effect.Effect<readonly User[]>
85	}
86	>()("@app/Users") {
87	static readonly layer = Layer.effect(
88	Users,
89	Effect.gen(function* () {
90	const http = yield* HttpClient.HttpClient
91	const findById = Effect.fn("Users.findById")(function* (id: UserId) {
92	const response = yield* http.get(`/users/${id}`)
93	return yield* HttpClientResponse.schemaBodyJson(User)(response)
94	})
95	const all = Effect.fn("Users.all")(function* () {
96	const response = yield* http.get("/users")
97	return yield* HttpClientResponse.schemaBodyJson(Schema.Array(User))(response)
98	})
99	return { findById, all }
100	})
101	)
102	}
103	```
104
105	Rules:
106	- Tag identifiers must be unique. Use `@app/ServiceName` pattern
107	- Service methods should have `R = never` (dependencies via Layer, not method signatures)
108	- Use `readonly` properties
109
110	See [references/services-and-layers.md](references/services-and-layers.md) for service-driven development, test layers, layer memoization, and full composition patterns.
111
112	## Schema.Class and Branded Types
113
114	Use `Schema.Class` for domain records. Brand all entity IDs and domain primitives:
115
116	```typescript
117	impo

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