This document explains how to install pygls and get started writing language servers that are based on it.
Before going any further, if you are not familiar with language servers and Language Server Protocol, we recommend reading following articles:
To get the latest release from PyPI, simply run:
pip install pygls
Alternatively, pygls source code can be downloaded from our GitHub page and installed with following command:
pip install git+https://github.com/openlawlibrary/pygls
Spin the Server Up
pygls is a language server that can be started without writing any additional code:
from pygls.server import LanguageServer server = LanguageServer('example-server', 'v0.1') server.start_tcp('127.0.0.1', 8080)
After running the code above, server will start listening for incoming
Json RPC requests on
Register Features and Commands
pygls comes with an API for registering additional features like
find all references,
go to definition, etc.
@server.feature(TEXT_DOCUMENT_COMPLETION, CompletionOptions(trigger_characters=[','])) def completions(params: CompletionParams): """Returns completion items.""" return CompletionList( is_incomplete=False, items=[ CompletionItem(label='Item1'), CompletionItem(label='Item2'), CompletionItem(label='Item3'), ] )
… as well as custom commands:
@server.command('myVerySpecialCommandName') def cmd_return_hello_world(ls, *args): return 'Hello World!'
lsprotocol.types module for the complete and canonical list of available features.
We recommend completing the tutorial, especially if you haven’t worked with language servers before.
To reveal the full potential of pygls (
TCP/STDIO communication, etc.) keep reading.