Lesson 4: Scalars

A scalar is an atomic data type. This includes strings, numbers, boolean values true and false, and null.

The following example is a bare document with a single scalar value.

My single value document.

The following example demonstrates a map with various scalar types of values.

greeting: Hello
favoriteNumber: 123
favoriteDessert: 3.14
favoriteChild: null
areYouASentientBeing: true
partyTime: 2021-12-31T23:59:59Z

Escaped characters

Escape

Escape means to remove special meaning from a character so it can be used literally.

Keys or values that contain the following characters must be escaped:

starts with a - character followed by a space
has a : character followed by a space
has a # character preceded by a space
all non-printable characters.

Escape a single character with single quotes, or all characters in a scalar with double quotes. Another option that escapes is using blocks covered in the next lesson.

The following is an example of some problem unescaped values and their corresponding escaped solutions.

Problem	Solution
- plums	'- plums'
Space: An Odyssey	'Space: An Odyssey'
The #3 YAML mistake	'The #3 YAML mistake'

Exercise 4.1: Spot the key with the problem value

Author: Szy de'Root
bookTitle: Docs: investment in productivity
publicationDate: 2021-12-31

See answer

The bookTitle corresponding value must be escaped because it has a : followed by a space.

The correct YAML is:

Author: Szy de'Root
bookTitle: 'Docs: investment in productivity'
publicationDate: 2021-12-31

It could also be escaped with double quotes:

Author: Szy de'Root
bookTitle: "Docs: investment in productivity"
publicationDate: 2021-12-31

Exercise 4.2: Spot the key with the problem value

Author: R2:D2
bookTitle: Lessons - From Observing Life
chapterTitle: Lesson #1
publicationDate: 2021-12-31