I'm surprised in a discussion of when to quote or not quote with YAML the dreaded "yes", "no", "true", "false", "on", and "off" booleans didn't come up.
Quoting the article:
> In YAML, you can write a string without quotes, if it doesn't have a special meaning.
Yeah, about that...
Is this even a question? I double quote ALL strings. In fact, my C background makes me use " in Python too, even though single quote ' is acceptable. Somehow " feels more __stringy__.
Quote strings, always.
For the love of God, save yourself pain. Always quote.