Effect Platform
Overview
@effect/platform provides cross-platform abstractions for:
- HTTP Client - Make HTTP requests
- HTTP Server - Build HTTP servers
- FileSystem - File operations
- KeyValueStore - Persistent storage
- Terminal - CLI interactions
- Worker - Background workers
HTTP Client
Installation
npm install @effect/platform
# For Node.js:
npm install @effect/platform-node
# For Bun:
npm install @effect/platform-bun
Basic Requests
import { HttpClient } from "@effect/platform";
import { NodeHttpClient } from "@effect/platform-node";
import { Effect } from "effect";
const program = Effect.gen(function* () {
const client = yield* HttpClient.HttpClient;
// GET request
const response = yield* client.get("https://api.example.com/users");
const data = yield* response.json;
return data;
}).pipe(Effect.provide(NodeHttpClient.layer));
Request Configuration
const program = Effect.gen(function* () {
const client = yield* HttpClient.HttpClient;
// POST with body
const response = yield* client.post("https://api.example.com/users", {
body: HttpClientRequest.jsonBody({ name: "Alice", email: "alice@example.com" }),
});
// With headers
const response = yield* client.get("https://api.example.com/protected", {
headers: { Authorization: "Bearer token123" },
});
// With timeout
const response = yield* client.get("https://api.example.com/slow").pipe(Effect.timeout("5 seconds"));
});
Response Handling
const program = Effect.gen(function* () {
const client = yield* HttpClient.HttpClient;
const response = yield* client.get("https://api.example.com/data");
// Parse as JSON
const json = yield* response.json;
// Parse as text
const text = yield* response.text;
// Get status
const status = response.status;
// Get headers
const contentType = response.headers["content-type"];
});
Schema Validation
import { HttpClient, HttpClientResponse } from "@effect/platform";
import { Schema } from "effect";
const User = Schema.Struct({
id: Schema.Number,
name: Schema.String,
email: Schema.String,
});
const program = Effect.gen(function* () {
const client = yield* HttpClient.HttpClient;
const response = yield* client.get("https://api.example.com/users/1");
// Validate response with schema
const user = yield* HttpClientResponse.schemaBodyJson(User)(response);
return user;
});
HTTP Server
Basic Server
import { HttpServer, HttpServerResponse } from "@effect/platform";
import { NodeHttpServer } from "@effect/platform-node";
import { Effect, Layer } from "effect";
import { createServer } from "node:http";
const app = HttpServer.router.empty.pipe(
HttpServer.router.get("/", HttpServerResponse.text("Hello, World!")),
HttpServer.router.get(
"/users",
HttpServerResponse.json([
{ id: 1, name: "Alice" },
{ id: 2, name: "Bob" },
]),
),
);
const ServerLive = NodeHttpServer.layer(createServer, { port: 3000 });
const program = Effect.gen(function* () {
yield* Effect.log("Server starting on port 3000");
yield* Effect.never; // Keep running
}).pipe(Effect.provide(HttpServer.router.Live(app)), Effect.provide(ServerLive));
Route Parameters
const app = HttpServer.router.empty.pipe(
HttpServer.router.get(
"/users/:id",
Effect.gen(function* () {
const params = yield* HttpServer.router.params;
const id = params.id;
return HttpServerResponse.json({ id, name: "User " + id });
}),
),
);
Request Body
import { HttpServerRequest } from "@effect/platform";
const app = HttpServer.router.empty.pipe(
HttpServer.router.post(
"/users",
Effect.gen(function* () {
const request = yield* HttpServerRequest.HttpServerRequest;
const body = yield* request.json;
// Or with schema validation
const validated = yield* HttpServerRequest.schemaBodyJson(CreateUser)(request);
return HttpServerResponse.json({ created: true, user: validated });
}),
),
);
FileSystem
Reading Files
import { FileSystem } from "@effect/platform";
import { NodeFileSystem } from "@effect/platform-node";
const program = Effect.gen(function* () {
const fs = yield* FileSystem.FileSystem;
const content = yield* fs.readFileString("./config.json");
const bytes = yield* fs.readFile("./image.png");
const exists = yield* fs.exists("./file.txt");
}).pipe(Effect.provide(NodeFileSystem.layer));
Writing Files
const program = Effect.gen(function* () {
const fs = yield* FileSystem.FileSystem;
yield* fs.writeFileString("./output.txt", "Hello, World!");
yield* fs.writeFile("./data.bin", new Uint8Array([1, 2, 3]));
yield* fs.appendFileString("./log.txt", "New log entry\n");
});
Directory Operations
const program = Effect.gen(function* () {
const fs = yield* FileSystem.FileSystem;
yield* fs.makeDirectory("./new-dir", { recursive: true });
const files = yield* fs.readDirectory("./src");
yield* fs.remove("./temp", { recursive: true });
yield* fs.copy("./source.txt", "./dest.txt");
yield* fs.rename("./old.txt", "./new.txt");
});
File Info
const program = Effect.gen(function* () {
const fs = yield* FileSystem.FileSystem;
const stat = yield* fs.stat("./file.txt");
console.log({
size: stat.size,
isFile: stat.type === "File",
isDirectory: stat.type === "Directory",
modified: stat.mtime,
});
});
KeyValueStore
Persistent key-value storage:
import { KeyValueStore } from "@effect/platform";
import { NodeKeyValueStore } from "@effect/platform-node";
const program = Effect.gen(function* () {
const store = yield* KeyValueStore.KeyValueStore;
yield* store.set("user:1", JSON.stringify({ name: "Alice" }));
const value = yield* store.get("user:1");
yield* store.remove("user:1");
const exists = yield* store.has("user:1");
}).pipe(Effect.provide(NodeKeyValueStore.layerFileSystem("./data")));
Terminal
CLI interactions:
import { Terminal } from "@effect/platform";
import { NodeTerminal } from "@effect/platform-node";
const program = Effect.gen(function* () {
const terminal = yield* Terminal.Terminal;
const name = yield* terminal.readLine;
yield* terminal.display(`Hello, ${name}!`);
}).pipe(Effect.provide(NodeTerminal.layer));
Complete Example: REST API
import { HttpServer, HttpServerResponse, HttpServerRequest } from "@effect/platform";
import { NodeHttpServer } from "@effect/platform-node";
import { Effect, Layer, Schema } from "effect";
import { createServer } from "node:http";
// Schemas
const CreateUser = Schema.Struct({
name: Schema.String,
email: Schema.String,
});
const User = Schema.Struct({
id: Schema.Number,
name: Schema.String,
email: Schema.String,
});
// In-memory store
let users: Schema.Schema.Type<typeof User>[] = [];
let nextId = 1;
// Routes
const app = HttpServer.router.empty.pipe(
HttpServer.router.get("/users", HttpServerResponse.json(users)),
HttpServer.router.post(
"/users",
Effect.gen(function* () {
const body = yield* HttpServerRequest.schemaBodyJson(CreateUser);
const user = { id: nextId++, ...body };
users.push(user);
return HttpServerResponse.json(user, { status: 201 });
}),
),
HttpServer.router.get(
"/users/:id",
Effect.gen(function* () {
const { id } = yield* HttpServer.router.params;
const user = users.find((u) => u.id === parseInt(id));
return user ? HttpServerResponse.json(user) : HttpServerResponse.json({ error: "Not found" }, { status: 404 });
}),
),
);
// Server
const ServerLive = NodeHttpServer.layer(createServer, { port: 3000 });
const main = HttpServer.serve(app).pipe(Effect.provide(ServerLive), Effect.catchAllCause(Effect.logError));
Effect.runPromise(main);
Best Practices
- Use Schema validation - Validate all external data
- Provide platform layers - NodeHttpClient.layer, etc.
- Handle errors - Network failures, file not found, etc.
- Use Effect.scoped for resources - Files, connections
- Configure timeouts - Prevent hanging requests
Additional Resources
For comprehensive platform documentation, consult ${CLAUDE_PLUGIN_ROOT}/references/llms-full.txt.
Search for these sections:
- "HTTP Client" for making requests
- "HTTP Server" for building servers
- "FileSystem" for file operations
- "KeyValueStore" for persistent storage
- "Terminal" for CLI interactions
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