multi-mode with markdown and language

Question

I swear there used to be something like this.

I'm writing a lot of Markdown with embedded code. I would like to have EMACS treat code in GitHum fenced code according to the default mode for that type of code. That is, if I write:

...and this excellent piece of code computes a function significant to number theory:

```python
def even(x):
    return (x % 2) == 0
```

I would like the code within the fences to be treated as Python while the code outside the fences is Markdown.

Answer 1

For markdown, I would strongly recommend using polymode.

Currently, polymode is distributed with a special mode that will allow you to edit these regions with the appropriate major mode.

If you're also using use-package you can enable it with:

(use-package polymode
  :ensure t
  :defer t)

(use-package poly-markdown
  :ensure polymode
  :defer t
  :mode ("\\.md" . poly-markdown-mode))

There's also some more details available in this answer:

https://emacs.stackexchange.com/a/27695/2653