observations and reports

YAML syntax was designed to be easily mapped to data types common to most high-level languages: list, hash, and scalar.^[3] Its familiar indented outline and lean appearance makes it especially suited for tasks where humans are likely to view or edit data structures, such as configuration files, dumping during debugging, and document headers (e.g. the headers found on most e-mails are very close to YAML). Although well-suited for hierarchical data representation, it also has a compact syntax for relational data as well.^[4] Its line and whitespace delimiters make it friendly to ad hoc grep/Python/Perl/Ruby operations. A major part of its accessibility comes from eschewing the use of enclosures like quotation marks, brackets, braces, and open/close-tags which can be hard for the human eye to balance in nested hierarchies.

[edit]Examples

[edit]Sample document

Data structure hierarchy is maintained by outline indentation.

---
receipt:     Oz-Ware Purchase Invoice
date:        2007-08-06
customer:
    given:   Dorothy
    family:  Gale

items:
    - part_no:   A4786
      descrip:   Water Bucket (Filled)
      price:     1.47
      quantity:  4

    - part_no:   E1628
      descrip:   High Heeled "Ruby" Slippers
      price:     100.27
      quantity:  1

bill-to:  &id001
    street: |
            123 Tornado Alley
            Suite 16
    city:   East Westville
    state:  KS

ship-to:  *id001

specialDelivery:  >
    Follow the Yellow Brick
    Road to the Emerald City.
    Pay no attention to the
    man behind the curtain.
...

Notice that strings do not require enclosure in quotations. The specific number of spaces in the indentation is unimportant as long as parallel elements have the same left justification and the hierarchically nested elements are indented further. This sample document defines a hash with 7 top level keys: one of the keys, “items”, contains a 2 element array (or “list”), each element of which is itself a hash with four keys. Relational data and redundancy removal are displayed: the “ship-to” hash content is copied from the “bill-to” hash’s content as indicated by the anchor (&) and reference (*) labels. Optional blank lines can be added for readability. Multiple documents can exist in a single file/stream and are separated by “—-“. An optional “…” can be used at the end of a file (useful for signaling an end in streamed communications without closing the pipe).