Although the documentation for this project is hosted on github as well, always use the hosted docs for the best experience.
This is the official repository for the Haskell implementation of the ABCI server and SDK for developing applications backed by the Tendermint replication engine. You can read more about Tendermint and the ABCI specs in their documentation.
To understand how to build a simple application using this library, see the literate haskell walkthrough.