Vim Syntax Highlighting for YSH

Right now we're doing YSH only, not OSH.

Here's an alternative plugin supports more features:

• https://github.com/sj2tpgk/vim-oil

Though I found an issue where it incorrectly highlighted single quotes within # comments.

So I am trying something simpler.

Notes

• The (nascent) "micro syntax" style supports only
  • comments
  • string literals

But maybe that is too minimal. I also like to highlight:

• \n within string literals (and outside perhaps)
• Within double quoted string literals:
  • $myvar
  • ${myvar}
  • $[myvar]

Command vs. Expression Mode

Users do have problems with this distinction.

I wonder if syntax highlighting can help. Here are the places it changes in YSH

var y = 42 + f(expr)
var y = ^[42 + f(expr)]
# const, setvar, setglobal

= 42 + f(expr)
call f(expr)

echo $[42 + f(expr)]
echo @[42 + f(expr)]

pp (42 + expr)
pp [42 + expr]

We also have:

proc p (; x, y) { ...

func f (x, y) { ...