Comment by georgewfraser

The language server protocol is revolutionary for providing features like intelligent autocomplete to text editors. It basically brings proper separation-of-concerns to language tooling. In particular, because it's based on JSON messages over sockets, you can implement the tooling for each language in that language. I'm the author of https://github.com/georgewfraser/vscode-javac which uses the Java compiler tree API to implement a Java language server---the task was made radically easier by being able to implement it in the target language.