If YAML ain’t markup language, what is it

markupyaml

I fail to see what makes YAML any less of a markup language than XML. The purpose of a markup language is to define the structure of a document, and YAML does exactly that (YAML stands for YAML ain't markup language).

What YAML should instead stand for is, Yet another markup language.

Best Answer

Here's the real story... :)

Clark, Oren and I started working on YAML in April 2001. Oren and Clark were part of the SML mailing list, which was trying to make XML simpler. I had just written a data serialization language for Perl called Data::Denter. Clark contacted me to tell me about an idea they had called YAML, which looked similar to Data::Denter syntax. Clark already had acquired yaml.org.

After a few months of us working together, I pointed out that YAML (which most definitely stood for Yet Another Markup Language at that time) was not really a markup language (marking up various elements of a text document) but a serialization language (textual representation of typed/cyclical data graphs). We all liked the name YAML, so we backronymed it to mean YAML Ain't Markup Language.

http://yaml.org/spec/ starts with:

YAML™ (rhymes with “camel”) is a human-friendly, cross language, Unicode based data serialization language designed around the common native data structures of agile programming languages.

I couldn't have said it better myself… :

Related Solutions

Json – the difference between YAML and JSON

Technically YAML is a superset of JSON. This means that, in theory at least, a YAML parser can understand JSON, but not necessarily the other way around.

See the official specs, in the section entitled "YAML: Relation to JSON".

In general, there are certain things I like about YAML that are not available in JSON.

As @jdupont pointed out, YAML is visually easier to look at. In fact the YAML homepage is itself valid YAML, yet it is easy for a human to read.
YAML has the ability to reference other items within a YAML file using "anchors." Thus it can handle relational information as one might find in a MySQL database.
YAML is more robust about embedding other serialization formats such as JSON or XML within a YAML file.

In practice neither of these last two points will likely matter for things that you or I do, but in the long term, I think YAML will be a more robust and viable data serialization format.

Right now, AJAX and other web technologies tend to use JSON. YAML is currently being used more for offline data processes. For example, it is included by default in the C-based OpenCV computer vision package, whereas JSON is not.

You will find C libraries for both JSON and YAML. YAML's libraries tend to be newer, but I have had no trouble with them in the past. See for example Yaml-cpp.

Python – How to parse a YAML file in Python

The easiest and purest method without relying on C headers is PyYaml (documentation), which can be installed via pip install pyyaml:

#!/usr/bin/env python

import yaml

with open("example.yaml", "r") as stream:
    try:
        print(yaml.safe_load(stream))
    except yaml.YAMLError as exc:
        print(exc)

And that's it. A plain yaml.load() function also exists, but yaml.safe_load() should always be preferred unless you explicitly need the arbitrary object serialization/deserialization provided in order to avoid introducing the possibility for arbitrary code execution.

Note the PyYaml project supports versions up through the YAML 1.1 specification. If YAML 1.2 specification support is needed, see ruamel.yaml as noted in this answer.

Also, you could also use a drop in replacement for pyyaml, that keeps your yaml file ordered the same way you had it, called oyaml. View synk of oyaml here

Best Answer

Related Solutions

Json – the difference between YAML and JSON

Python – How to parse a YAML file in Python

Related Topic