launchdarkly-server-sdk: Server-side SDK for integrating with LaunchDarkly

[ apache, library, web ] [ Propose Tags ]

Please see the README on GitHub at

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Versions [faq] 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 2.0.0, 2.0.1, 2.0.2
Change log
Dependencies aeson (>= && <1.6), attoparsec (>= && <0.14), base (>=4.7 && <5), base16-bytestring (>= && <0.2), bytestring (>= && <0.11), bytestring-conversion (>=0.3.1 && <0.4), clock (==0.8.*), containers (>= && <0.7), cryptohash (>=0.11.9 && <0.12), exceptions (>=0.10.2 && <0.11), extra (>=1.6.17 && <1.8), generic-lens (>= && <2.1), hashtables (>= && <1.3), hedis (>=0.12.7 && <0.13), http-client (>=0.6.4 && <0.8), http-client-tls (>= && <0.4), http-types (>=0.12.3 && <0.13), iso8601-time (>=0.1.5 && <0.2), lens (>=4.17.1 && <4.20), lrucache (>= && <1.3), monad-logger (>=0.3.30 && <0.4), mtl (>=2.2.2 && <2.3), pcre-light (>= && <0.5), random (>=1.1 && <1.3), retry (>= && <0.9), scientific (>= && <0.4), semver (>=0.3.4 && <0.4), text (>= && <1.3), time (>= && <1.11), unordered-containers (>= && <0.3), uuid (>=1.3.13 && <1.4), vector (>= && <0.13) [details]
License Apache-2.0
Copyright 2019 Catamorphic, Co
Author LaunchDarkly
Category Web
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Source repo head: git clone
Uploaded by launchdarkly at 2020-10-15T16:11:31Z
Distributions NixOS:2.0.2
Downloads 1013 total (8 in the last 30 days)
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Status Hackage Matrix CI
Docs available [build log]
Last success reported on 2020-10-15 [all 1 reports]


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For package maintainers and hackage trustees

Readme for launchdarkly-server-sdk-2.0.2

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LaunchDarkly Server-side SDK for Haskell


The LaunchDarkly Server-side SDK for Haskell is designed primarily for use in multi-user systems such as web servers and applications. It follows the server-side LaunchDarkly model for multi-user contexts. It is not intended for use in desktop and embedded systems applications.

LaunchDarkly overview

LaunchDarkly is a feature management platform that serves over 100 billion feature flags daily to help teams build better software, faster. Get started using LaunchDarkly today!

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Getting started

Download a release archive from the GitHub Releases for use in your project. Refer to the SDK documentation for complete instructions on getting started with using the SDK.

Learn more

Check out our documentation for in-depth instructions on configuring and using LaunchDarkly. You can also head straight to the complete reference guide for this SDK.


We run integration tests for all our SDKs using a centralized test harness. This approach gives us the ability to test for consistency across SDKs, as well as test networking behavior in a long-running application. These tests cover each method in the SDK, and verify that event sending, flag evaluation, stream reconnection, and other aspects of the SDK all behave correctly.


We encourage pull requests and other contributions from the community. Check out our contributing guidelines for instructions on how to contribute to this SDK.

About LaunchDarkly

  • LaunchDarkly is a continuous delivery platform that provides feature flags as a service and allows developers to iterate quickly and safely. We allow you to easily flag your features and manage them from the LaunchDarkly dashboard. With LaunchDarkly, you can:
    • Roll out a new feature to a subset of your users (like a group of users who opt-in to a beta tester group), gathering feedback and bug reports from real-world use cases.
    • Gradually roll out a feature to an increasing percentage of users, and track the effect that the feature has on key metrics (for instance, how likely is a user to complete a purchase if they have feature A versus feature B?).
    • Turn off a feature that you realize is causing performance problems in production, without needing to re-deploy, or even restart the application with a changed configuration file.
    • Grant access to certain features based on user attributes, like payment plan (eg: users on the ‘gold’ plan get access to more features than users in the ‘silver’ plan). Disable parts of your application to facilitate maintenance, without taking everything offline.
  • LaunchDarkly provides feature flag SDKs for a wide variety of languages and technologies. Check out our documentation for a complete list.
  • Explore LaunchDarkly