csharp.el

(require 'csharp-mode)
(require 'omnisharp)
(add-hook 'csharp-mode-hook 'omnisharp-mode)
(eval-after-load
 'company
 '(add-to-list 'company-backends 'company-omnisharp))
(add-hook 'csharp-mode-hook #'company-mode)
(add-hook 'csharp-mode-hook #'flycheck-mode)

(eval-after-load
  'company
  '(add-to-list 'company-backends #'company-omnisharp))

(defun my-csharp-mode-setup ()
  (omnisharp-mode)
  (company-mode)
  (flycheck-mode)

  (setq indent-tabs-mode nil)
  (setq c-syntactic-indentation t)
  (c-set-style "ellemtel")
  (setq c-basic-offset 4)
  (setq truncate-lines t)
  (setq tab-width 4)
  (setq evil-shift-width 4)

  ;csharp-mode README.md recommends this too
  ;(electric-pair-mode 1)       ;; Emacs 24
  ;(electric-pair-local-mode 1) ;; Emacs 25

  (local-set-key (kbd "C-c r r") 'omnisharp-run-code-action-refactoring)
  (local-set-key (kbd "C-c C-c") 'recompile))

(add-hook 'csharp-mode-hook 'my-csharp-mode-setup t)

(when (darwin?)
  ;; You'll need to do:
  ;;   $ brew install omnisharp/omnisharp-roslyn/omnisharp-mono
  ;; before you can use this.
  ;; You'll also probably want to install VS Code and the .NET core SDK.
  ;; You'll also need to M-x omnisharp-install-server
  ;; Then do M-x omnisharp-start-omnisharp-server
  (setq omnisharp-server-executable-path "/usr/local/bin/omnisharp"))