A modification to mhj/show-project-explorer as requested by Benjamín Buccianti

mhj-explore-toggle-mod.el

(defun mhj/show-project-explorer ()
  "Project dired buffer on the side of the frame.
Shows the projectile root folder using dired on the left side of
the frame and makes it a dedicated window for that buffer."
  (let ((buffer (dired-noselect (projectile-project-root))))
    (progn
      (display-buffer-in-side-window buffer '((side . left) (window-width . 0.2)))
      (set-window-dedicated-p (get-buffer-window buffer) t)
      (select-window (get-buffer-window buffer)))))