YS Comment Syntax

What is the syntax for comments in YS?

Well that's simple.

YS code is YAML, so the comment syntax is the same as YAML.

Well, there's a little bit more to it than that.

YAML Comments

Yes. YAML comments are valid in YS code.

There's no way they couldn't be. (Not without breaking the laws of YAML Physics!)

Comments in YAML start with # and continue to the end of the line.

Clojure comments use ; to the end of the line.

For a while, YS also supported ; as a comment character. Only in code mode, of course.

YAML and Multi-line Scalars

One: thing I don't see enough of in people's YAML is splitting long strings into multiple lines.

In YAML, with plain, folded and quoted scalars, you can split a line anywhere you want.

One: thing I don't see enough
     of in people's YAML is
     splitting long strings
     into multiple lines.

You can even start the scalar on a new line.

One:
  thing I don't see enough of in people's YAML is
  splitting long strings into multiple lines.

But one thing you can't do is put comments in the middle of a multi-line scalar.

say:
  One thing I rarely see enough of in YAML files  # LINE 1
  is splitting long strings into multiple lines.

That's an error.

You actually don't need to put comments in multi-line scalars much in YAML...

But in YS the need comes up more often.

$ ys -e 'say:
  read-line()   # Read line from stdin
    .words()    # Split into words
    .reverse()  # Reverse the words
    .joins()    # Join the words with a space'
Compile error: while parsing a block mapping
 in reader, line 2, column 1:
    say:
    ^
expected <block end>, but found '<scalar>'
 in reader, line 4, column 5:
        .words()    # Split into words
        ^

Those comments would be nice, but they're not valid YAML.

Luckily YS has a solution for this. It has a special comment syntax (only in code mode).

$ ys -e 'say:
  read-line()   \"Read line from stdin"
    .words()    \"Split into words"
    .reverse()  \"Reverse the words"
    .joins()    \"Join the words with a space"'
YS is YAML
YAML is YS

Couldn't have said it better myself!

Comments