How Metals and LSP allow you to use your favorite editor for Scala

Chris Kipp

A huge thank you

Tomasz

Godzik

Ólafur Geirsson

Gabriele Petronella

What is LSP?

What is Metals?

What is LSP?

2 Approaches

IDE

Features

Editor

Client

Server

Editor

Features

the problem

Features

Editor

Server

Client

???

LSP

The idea behind the Language Server Protocol (LSP) is to standardize the protocol for how tools and servers communicate, so a single Language Server can be re-used in multiple development tools, and tools can support languages with minimal effort.

https://microsoft.github.io/language-server-protocol/overview

LSP

Created in 2016
Headed up by Microsoft while developing VS Code and TypeScript
Now also sponsored by Codenvy, Red Hat and Sourcegraph

LSP

https://microsoft.github.io/language-server-protocol/overview

LSP

[Trace - 11:53:10 AM] Sending notification 'window/showMessage'
Params: {
  "type": 4,
  "message": "Compiling root 2s"
}


[Trace - 11:53:10 AM] Sending notification 'textDocument/publishDiagnostics'
Params: {
  "uri": "file:///.../test-project/src/main/scala/example/Other.scala",
  "diagnostics": []
}


[Trace - 11:53:10 AM] Sending notification 'window/logMessage'
Params: {
  "type": 4,
  "message": "INFO  time: compiled root in 2.67s"
}