lsp

lsp is a library for building language servers, handling:

• JSON-RPC transport
• Keeping track of the document state in memory with the Virtual File System (VFS)
• Responding to notifications and requests via handlers
• Setting the server capabilities in the initialize request based on registered handlers
• Dynamic registration of capabilities
• Cancellable requests and progress notifications
• Publishing and flushing of diagnostics

It is part of the lsp family of packages, along with lsp-test and lsp-types

For more information, check https://github.com/haskell/lsp/blob/master/README.md