YAML Sparse Sequences

YAML Sparse Sequences are sequences (usually large sequences) that may contain only a small number of non-null entries

YAML allows to serialize such sequences using the mapping style with an explicit sequence type family.

note

The only supported keys are integers, serving as zero-based sequence entry indices.

For example:

Sparse Sequence
my-sequence: !seq
 2: Third entry
 4: ~

That is converted into an identical in-memory sequence, which has a separate identity:

Coverted Sparse Sequence
my-sequence:
 - ~
 - ~
 - Third entry
 - ~
 - ~

note

Note that it is possible to serialize such sparse sequences using the null implicit type family, but it is awkward!

YAML Sparse Sequences​