(require 'pyenv-mode)

(defun projectile-pyenv-mode-set ()
  "Set pyenv version matching project name."
  (let ((project (projectile-project-name)))
    (if (member project (pyenv-mode-versions))
        (pyenv-mode-set project)
      (pyenv-mode-unset))))

(add-hook 'projectile-after-switch-project-hook 'projectile-pyenv-mode-set)