Platform Layers

Master Effect platform layer provision for cross-platform applications. Use this skill when structuring applications that use Effect platform abstractions to ensure portability across Node.js and Bun environments.

The Golden Rule

Application code uses abstract interfaces. Platform-specific layers are provided either at the program entry point or inside a runtime-facing adapter module's defaultLayer.

// Application code - platform agnostic
import { Effect, FileSystem, Path, pipe } from 'effect';

const readConfig = Effect.gen(function* () {
	const fs = yield* FileSystem.FileSystem;
	const path = yield* Path.Path;
	const configPath = path.join('config', 'app.json');
	return yield* fs.readFileString(configPath);
});