I’m attempting to match the leading - characters in a Markdown list such as this:

---
What were the key things that drove me to make a switch?
- No Database -- you 
- Tremendous Support -- the 
- Sane Folder Structure -- everything
- Rapid Development -- there
- Blog Post Folders -- granted
- Asset Pipeline -- Grav
- Twig — yes

The regex that isn’t working looks like this:

{    name = 'text.html.markdown.list';
     match = '(?<=\n)-(?= )|(?<!.)-(?= )';
},

What did I get wrong?

Bob
-------------------
Robert J. Rockefeller
Richmond Hill, GA
www.bobrockefeller.com