Specifying the string-value 'yes' in a YAML property

Question

Consider the following document:

foo:
  bar: Yes

According to the spec, this should be interpreted as a Boolean, not as a String.

However, it seems that this document yields the same interpretation:

foo:
  bar: 'Yes'

If I misunderstand, and 'Yes' (in quotes) should in fact be understood as a String-typed value, where in the specs can I find justification for this?

However, if I do interpret correctly, and these documents are equivalent according to spec, how can I specify a string with the value "Yes" as the value of a YAML property?

Answer 1

It depends ;-)

In YAML 1.1 the bool type is defined as following:

A Boolean represents a true/false value. Booleans are formatted as English words (“true”/“false”, “yes”/“no” or “on”/“off”) for readability and may be abbreviated as a single character “y”/“n” or “Y”/“N”.

In YAML 1.2 the bool type is defined as following:

Booleans: [ true, True, false, FALSE ]

Assigning the value Yes to a key is done via quotes:

foo: 'Yes'
bar: "Yes"

Assigning a boolean and to be compatible with future versions of YAML parsers should be done with

foo: false
bar: True

You can play around yourself with YAML syntax at the https://yamlvalidator.com/