VimPlugin: deoplete
From wikinotes
Deoplete aims to serve purely as an autocompleter.
It is the first asynchronous autocompleter for vim, and is much faster than VimPlugin: YouCompleteMe.
It has mostly been superceeded by the LSP plugins like VimPlugin: Coc.nvim.
WARNING:
If deoplete complains about requirements, try reinstalling from pip rather than package manager (newer).
pip install msgpack
Complement Plugins
deoplete deoplete-solargraph # ruby deoplete-jedi # python
