As a c# coder and emacs user, I've been playing with omnisharp (https://github.com/OmniSharp/omnisharp-emacs). It mostly seems to be working - following the instructions on that page I got company integrated well.
However m-x doesn't find almost all of the helm integrations, omnisharp-helm-find-usages and the like. helm-imenu works, with all the functions from the local file listed.
A brief look at the source shows that the helm integrations are included under this conditional:
(when (require 'helm-grep nil 'noerror)
...using m-x, I can't find helm-grep. I have helm-grep-mode and helm-grep-help, but no individual helm-grep. I can't find a package called that on elpa or melpa either.
I thought maybe I need to require 'helm before omnisharp in my init.el, but the docs linked above don't actually ask me to require 'omnisharp, just to add the hook to csharp-mode.