It's kind of hard to fully appreciate how powerful polymode is without actually _using_ it. When you use an editor that can mostly-understand the syntax behind markup like fenced markdown code blocks like this:
```ruby
puts "Hi"
```
You may be used to native syntax highlighting take over, but while you're in polymode, moving the cursor into the Ruby portion of the code actually activates Ruby-mode - any code checking (with something like flymake) works as expected, any major-mode specific actions that reformat code like M-q or == (while evil is active) will do what you expect, and polymode isn't just limited to fenced markdown.
Like the linked article demonstrates, polymode is super flexible. I myself wrote my own, small polymode that watches for comments like /* python */ that precede literal string blocks (which look like ''print("Hi")'' and are usually multi-line) in nix code to transform regions into their native modes (it doesn't need to just be python) and it's really great.
```ruby
puts "Hi"
```
You may be used to native syntax highlighting take over, but while you're in polymode, moving the cursor into the Ruby portion of the code actually activates Ruby-mode - any code checking (with something like flymake) works as expected, any major-mode specific actions that reformat code like M-q or == (while evil is active) will do what you expect, and polymode isn't just limited to fenced markdown.
Like the linked article demonstrates, polymode is super flexible. I myself wrote my own, small polymode that watches for comments like /* python */ that precede literal string blocks (which look like ''print("Hi")'' and are usually multi-line) in nix code to transform regions into their native modes (it doesn't need to just be python) and it's really great.
You can see an animated description of this here: https://twitter.com/leothrix/status/1597327756102336512
edit: my fenced block example was weird