Build R package from GNU Emacs on Windows 10

I use Windows 10 machine, at work, with GNU Emacs installed from choco repository. Script from my article Run shiny R application from Emacs was not working like in my old Windows 7. First thing is that it was not founding my R binary and I’ve got error:

apply: Spawning child process: Invalid argument

First thing was adding path to R binary second issue was path to Root of the package

Here is first function based on the one from previous article:

(defun call-r-command (command-list)
  "run R command in shell buffer window

  if there is displayed buffer that have shell it will use that window"
  (let* ((name "*R*")
         (new-buffer (get-buffer-create name))
         (old-buff (get-buffer name))
         ;; run R command
         (script-proc-buffer
          (apply 'make-comint-in-buffer
                 "script"
                 new-buffer
                 "c:/Program Files/R/R-3.5.2/bin/R.exe"
                 nil
                 command-list))
         ;; if there is *R* buffer try to find its window
         (old-window (if old-buff (get-buffer-window old-buff)))
         ;; use old window or find any that have shell mode
         (window (or old-window
                     (get-window-with-mode '(comint-mode eshell-mode))))
       (script-proc (get-buffer-process script-proc-buffer)))
    ;; reuse window or create new one
    (if window
        (set-window-buffer window new-buffer)
      (switch-to-buffer-other-window new-buffer))))

This function execute R command, so my new shiny function is shorter

(defun shiny ()
  "run shiny R application in shell buffer"
  (interactive)
  (let ((R (concat "shiny::runApp('" default-directory "')")))
    (call-r-command `("-e" ,R "--no-save"))))

Next is function that return root of git repo (since my R package is also git repo):

(defun shell-line (command)
  "Function execute shell command and return the result as single line"
  (replace-regexp-in-string "\n" "" (shell-command-to-string command)))

The problem with git on Windows 10 in GNU Emacs (or because of shell-command-to-string function) is that path is in Unix format not in Windows format, so I need to fix the path to use it in my R calling script.

(defun git-root-repo ()
  "Function return root of the git repo"
  (interactive)
  (replace-regexp-in-string "/mnt/c/" "c:/" (shell-line "git rev-parse --show-toplevel")))

Now my final function that build the R package:

(defun build-r-package ()
  "Build R package using git root directory as path to R package"
  (interactive)
  (call-r-command `("CMD" "INSTALL" ,(git-root-repo))))

Missing function for finding buffer with same major mode can be found in my previous article Run shiny R application from Emacs.