YAML - Block Sequences

The block sequences of YAML represent a series of nodes. Each item is denoted by a leading “-“ indicator. Note that the “-“ indicator in YAML should be separated from the node with a white space.

The basic representation of block sequence is given below −

block sequence:
··- one↓
  - two : three↓


Observe the following examples for a better understanding of block sequences.

Example 1

port: &ports
  adapter:  postgres
  host:     localhost

  database: myapp_development
  <<: *ports

The output of block sequences in JSON format is given below −

   "port": {
      "adapter": "postgres",
      "host": "localhost"
   "development": {
      "database": "myapp_development",
      "adapter": "postgres",
      "host": "localhost"