Add Effeck to an existing project

Install Effeck's packages in a project that has a package.json, and check that the compiler runs. Then set up the build.

1. Check package.json

package.json must have "type": "module". If it does not, ask the user before you add it: it changes how Node loads the project's .js files.

If package.json depends on a version of effect other than 4.0.5, stop and ask the user. The Effeck runtime requires effect 4.0.5 exactly.

2. Install the packages

With Bun, run:

bun add effeck-runtime@0.0.1 effect@4.0.5 @effect/platform-node@4.0.5
bun add -d effeck@0.0.1 effeck-vite@0.0.1 vitest@5.0.5 @effect/vitest@4.0.5

With npm, run:

npm install --save-exact effeck-runtime@0.0.1 effect@4.0.5 @effect/platform-node@4.0.5
npm install --save-dev --save-exact effeck@0.0.1 effeck-vite@0.0.1 vitest@5.0.5 @effect/vitest@4.0.5

Keep these versions. effeck-runtime checks Effect's version when it loads, so keep effect, @effect/platform-node, and @effect/vitest at 4.0.5. effeck, effeck-runtime, and effeck-vite are released together; keep them at one version.

Keep optional dependencies enabled. effeck gets its native compiler from one optional dependency per platform, such as effeck-darwin-arm64. If an install skips them, for example with npm install --omit=optional, effeck cannot find its binary and exits with an error.

3. Check the compiler

npx effeck --version

The output is:

Effeck 0.0.1 (TypeScript 7.1.0-dev)

Next

Set up the build. For React, Vue, or Svelte with Vite, read React, Vue, or Svelte. For other Vite or Vitest projects, read Vite and Vitest. Without a bundler, read Build with the effeck CLI. For another bundler, step 3 of Set up Effeck says what to do.