YAML Sequences

Learn how YAML sequences work as collections (like lists or arrays) with block style (using dashes) and flow style (using square brackets), including nested sequences.

A YAML file is rarely used to describe a simple scalar. Most of the time, it describes a collection.

YAML collections can be a sequence or a mapping of elements.

In YAML, the collection is represented with proper sequence styles.

YAML sequences are the equivalent of lists, arrays, etc. of programming languages.

The individual items of a sequence can have any type (strings, integers, floating-point numbers, mappings, or sequences)

Sequences can be created in two equivalent ways:

Block Style version

Sequences can be written in block style, using one line for each item in the sequence, with each line starting with a dash (-):

menu:
-  pizza
-  pasta
-  hamburger
-  steak
-  salad

Flow Style version

Sequences can be written in flow style using commas to separate the items and enclosing them in square brackets ([val1, val2, ...]).

menu: [pizza, pasta, hamburger, steak, salad]

Nested Sequences

Sequences can also be nested.

The following examples are all equivalent:

data:  [[1,  2],  [3,  4]]

data:
-
  - 1
  - 2
-
  - 3
  - 4

data:
- - 1
  - 2
- - 3
  - 4