Could you provide an example of what this desugars to? I'm not sure I understand.

You can simply use string.replace() with a global regex.

Dynamic patterns require escaping, resulting in unnecessary complexity and overhead.

Yes, you are (of course) able to replace all occurrences today. However, you either need to call replace multiple times or pollute your code with a regex. This would certainly improve the readability.

Why would using regex pollute your code?

It depends on who you ask; however the thinking is often:

* They can indicate poor parsing (ie can't read xml with regex) and failure to use programmatic methods (e.g parsing command output rather than making syscalls)

* regexes are very easy to write incorrectly without being obviously wrong

* regexes are often overkill for a direct match

* regexes invite people to make it more complex rather than restructure surrounding code

* regexs are comparatively more expensive than alternative code

* to work on the codebase you are now required to understand regex in general and this particular implementations quirks as well

I often use regexes, and I often choose not to use regexes.

Not sure what you mean? This doesn't add or use any new syntax, let alone syntactic sugar. It's a new builtin method.