How to install sage-shell-mode with Emacs 25.1?

Question

I would like to install sage-shell-mode. Now I read the README, and it indicated that with MELPA added to my package archive list I should be able to install sage-shell-mode with (after pressing M+x, of course) package-install sage-shell-mode. But this failed for me (i.e., sage-shell-mode was not found). Here is my ~/.emacs file, most notably this is how I enabled my package archives:

(package-initialize)
...
(add-to-list 'package-archives  (quote
(("gnu" . "http://elpa.gnu.org/packages/")
    ("melpa" . "http://melpa.org/packages/")
    ("marmalade" . "https://marmalade-repo.org/packages/")
    ("melpa-stable" . "http://stable.melpa.org/packages/")
    )))

Now I'm wondering if I made a mistake or whether sage-shell-mode is for whatever reason incompatible with Emacs 25.1. I have also run package-refresh-contents too, since I last updated my ~/.emacs file.

Answer 1

I loaded up MELPA and see sage-shell-mode listed. I don't know if this will solve the problem, but I've run into problems before with multiple package archives loading.

Here is a function I use to clear the list of packages and add MELPA. Don't forget to refresh the package list after this:

(defun my-package-load-melpa-only ()
  "Load package manager with MELPA only"
  (interactive)
  (if (eq nil (featurep 'package))  ; check if package feature is loaded
      ((require 'package)
       (package-initialize)
       (message "Initializing package manager")))
  (cond (
   (boundp 'package-archives)
   (setq package-archives '())
   ))
  (add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/"))
)

Then I would try finding the package in the package list mode (package-list-packages) if installing the mode still doesn't work.