YAML Field Notes - Scalars, Anchors, and Structures

April 13, 2026

Practical patterns for writing expressive and reusable YAML

Scalars

Folded Scalar

yaml

name: Folded Scalar. Replaces 
 with a space
command: >
    put commands here, that may
    go off screen.

Multiline/Block Scalar

yaml

name: Multiline Scalar. Use where 
 is signifact.
command: |
    command one -a arg_1
    command two -a arg_1

Anchors & Aliases

Anchors and aliases in YAML provide a convenient way to reuse data and avoid duplication within a YAML document. They are particularly useful for defining default configurations and inheriting values across multiple sections of the document.

yaml

defaults: &defaults
  username: guest
  password: guest
 
admin:
  <<: *defaults
  password: secret

Lists and Hashmaps

Inline List + Inline Map

yaml

colors: [red, green, blue]
person: {name: John Doe, age: 30}

Matrix/Matrices

Aka. a list of lists

yaml

matrix:
  - [1, 2, 3]
  - [4, 5, 6]
  - [7, 8, 9]