posthog-effect

Effect bindings for PostHog

Installation

First, ensure you have effect (version 3.0.0 or later) and posthog-node (version 5.0.0 or later) installed.

pnpm add effect posthog-effect

Next, install the @jrkienle/posthog package, which integrates Effect and PostHog.

pnpm add @jrkienle/posthog

Setup

Before you can use @jrkienle/posthog, you'll need to provide a Config value for POSTHOG_API_KEY. This is usually done by providing the value as an env var.

Usage

To use the package, simply provide the default service implementation to your program and call a function from the PostHog client:

import { PostHogClient } from '@jrkienle/posthog-effect';
import { Effect } from 'effect';

// Using the service
const program = Effect.gen(function* () {
  const postHog = yield* PostHogClient;

  const flags = yield* postHog.evaluateFlags('distinct_id_of_user');
  if (flags.isEnabled('flag-key')) {
    // Do something differently for this user
    // Optional: fetch the payload
    const matchedFlagPayload = flags.getFlagPayload('flag-key');
  }
});

// Providing the implementation
const runnable = Effect.provide(program, PostHogClient.Default);

// Ran successfully
Effect.runPromise(runnable);

Additionally, you can provide a value for the PostHogClientOptions , which will be used when initializing the PostHog client:

import { PostHogClient, PostHogClientOptions } from '@jrkienle/posthog-effect';
import { Effect } from 'effect';

const program = Effect.gen(function* () {
  const postHog = yield* PostHogClient;
});

const runnable = program.pipe(
  PostHogClient.default,
  Effect.provideService(PostHogClientOptions, {});
);

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.

Please make sure to update tests as appropriate.

License

This package is licensed under the MIT License. See LICENSE.

TODO

This package isn't complete yet. There are a few items I'll be taking care of in future releases:

• Adding fetch and on methods to PostHogClient.
• Setting up CI (need to run my own Forgejo instance first)
• Adding docs / doc comments
• Adding non-client methods

More coming soon!