Thrift is a serialization and remote procedure call (RPC) framework used for cross-service communication. Most services at Facebook communicate via Thrift because it provides a simple, language-agnostic protocol for communicating with structured data. Thrift can already be used in programming languages such as C++, Python, and Java using fbthrift. We are also open-sourcing Thrift support for Haskell (hsthrift).
The hsthrift package includes the full collection of tools and libraries for using Thrift in your own Haskell projects. The Haskell Thrift compiler generates the Haskell code needed to communicate with other Thrift services, and the included libraries allow you to build both Thrift clients and servers in Haskell. Haskell Thrift is fully compatible with all other fbthrift languages, so your Haskell project can freely communicate with other services no matter what language they are implemented in!
Source: Hsthrift: Open-sourcing Thrift for Haskell, an article by Noam Zilberstein and Simon Marlow.