Metals is a language server for Scala that is developed at the Scala Center along with contributors from the community.
Release notes: https://scalameta.org/metals/blog/2019/01/24/tin.html
Accompanying blog post on low-memory symbol indexing with bloom filters: https://scalameta.org/metals/blog/2019/01/22/bloom-filters.html
Try it out with Visual Studio Code, Atom, Vim, Sublime Text and Emacs 