Haskell SDK reference
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Last edited: May 19, 2022
Overview
This topic documents how to get started with the Haskell SDK, and links to reference information on all of the supported features.
LaunchDarkly's SDKs are open source. In addition to this reference guide, we provide source, API reference documentation, and a sample application:
| Resource | Location |
|---|---|
| SDK API documentation | SDK API docs |
| GitHub repository | haskell-server-sdk |
| Sample application | hello-haskell-server |
| Published module | Hackage |
Getting started
Follow the steps below to get started using the LaunchDarkly SDK in your Haskell application.
The root module of the SDK LaunchDarkly.Server re-exports the entire project.
Here is an example:
import LaunchDarkly.Server
After you import and install the SDK, create a single shared instance of Client. Specify your SDK key to authorize your application to connect to a particular environment within LaunchDarkly.
Here's how:
client :: IO Clientclient = makeClient $ makeConfig "YOUR_SDK_KEY"
It's important to make Client a singleton. The client instance maintains an internal state that allows LaunchDarkly to serve feature flags without making any remote requests. Do not instantiate a new client with every request.
You can use client to check which variation a particular user will receive for a given feature flag.
Here's how:
boolVariation client "YOUR_FLAG_KEY" (makeUser "abc") False
Shutting down
Lastly, shut down the client when your application terminates. To learn more, read Shutting down.
Supported features
This SDK supports the following features: