Introduction to Effect Platform

The effect package includes platform modules for building platform-independent abstractions in environments such as Node.js, Deno, Bun, and browsers.

With these modules, you can integrate abstract services like FileSystem or Terminal into your program. When assembling your final application, you can provide specific layers for the target platform using the corresponding packages:

• @effect/platform-node for Node.js or Deno
• @effect/platform-bun for Bun
• @effect/platform-browser for browsers

Stable Modules

The following modules are stable and their documentation is available on this website:

Installation

The platform modules are included in the effect package, so no additional installation is required. See Installation for how to install effect itself.

Platform-specific packages such as @effect/platform-node are only needed to run your program on a concrete platform, as shown in the sections below.

Getting Started with Cross-Platform Programming

Here’s a basic example using the Path module to create a file path, which can run across different environments:

Example (Cross-Platform Path Handling)

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import { Effect, Path } from "effect"
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const program = Effect.gen(function* () {
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  // Access the Path service
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  const path = yield* Path.Path
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  // Join parts of a path to create a complete file path
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  const mypath = path.join("tmp", "file.txt")
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  console.log(mypath)
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  return mypath
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})
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Effect.runSync(program.pipe(Effect.provide(Path.layer))) // => "tmp/file.txt"

Running the Program in Node.js or Deno

First, install the Node.js-specific package:

npm install @effect/platform-node@rc

pnpm add @effect/platform-node@rc

yarn add @effect/platform-node@rc

deno add npm:@effect/platform-node@rc

Update the program to load the Node.js-specific context:

Example (Providing Node.js Context)

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import { Effect, Path } from "effect"
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import { NodeServices, NodeRuntime } from "@effect/platform-node"
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const program = Effect.gen(function* () {
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  // Access the Path service
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  const path = yield* Path.Path
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  // Join parts of a path to create a complete file path
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  const mypath = path.join("tmp", "file.txt")
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  console.log(mypath)
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})
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NodeRuntime.runMain(program.pipe(Effect.provide(NodeServices.layer)))

Finally, run the program in Node.js using tsx, or directly in Deno:

npx tsx index.ts

pnpm dlx tsx index.ts

yarn dlx tsx index.ts

deno run index.ts
# or

deno run -RE index.ts
# Output: tmp/file.txt
# (granting required Read and Environment permissions without being prompted)

Running the Program in Bun

To run the same program in Bun, first install the Bun-specific package:

bun add @effect/platform-bun@rc

Update the program to use the Bun-specific context:

Example (Providing Bun Context)

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import { Effect, Path } from "effect"
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import { BunServices, BunRuntime } from "@effect/platform-bun"
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const program = Effect.gen(function* () {
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  // Access the Path service
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  const path = yield* Path.Path
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  // Join parts of a path to create a complete file path
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  const mypath = path.join("tmp", "file.txt")
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  console.log(mypath)
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})
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BunRuntime.runMain(program.pipe(Effect.provide(BunServices.layer)))

Run the program in Bun:

bun index.ts
tmp/file.txt