Software Engineer at SideCI, Inc. / RuboCop core developer
A parser based syntax highlighter
It has an elegant syntax that is natural to read and easy to write. https://www.ruby-lang.org/en/
Definitely. The syntax is elegant. But it is too complex sometimes. So, syntax highlighters for Ruby are difficult and easy to break.
For example, probably your editor cannot correctly highlight
% %s%% %%%% or
def end(def:def def;end)end (They are valid Ruby programs!).
Yeah, it is edge cases. In real cases, some syntax highlighter cannot correctly highlight a here document.
I'll talk a robust syntax highlighter for Ruby, it is Iro gem and Iro.vim. The highlighter never break since it uses Ripper to highlight code.