YAML Cheat Sheet

YAML, which stands for “YAML Ain’t Markup Language,” is a human-readable data serialization language that is often used for configuration files and data exchange between programming languages. It was first introduced in 2001 and has since become a popular choice for developers due to its simplicity and ease of use.

One of the main advantages of YAML is its readability. Unlike other data serialization formats, such as JSON or XML, YAML is designed to be easy for humans to read and write. This makes it a great choice for configuration files, where developers need to quickly and easily understand the settings and options being used.

Another advantage of YAML is its flexibility. It can be used to represent a wide range of data structures, including lists, dictionaries, and nested objects. This makes it a great choice for data exchange between different programming languages, as it can be easily parsed and understood by a variety of tools and libraries.

YAML is also highly customizable, with support for comments, anchors, and aliases. This allows developers to create complex data structures and reuse them throughout their codebase, making it easier to maintain and update their applications over time.

Basic Syntax

Syntax	Description
key: value	A key-value pair separated by a colon.
- item	A list item, indicated by a hyphen.
# comment	A comment, indicated by a hash symbol.

Data Types

Type	Example	Description
String	""hello""	A sequence of characters.
Number	42	A numeric value.
Boolean	true or false	A logical value.
Null	null	A value that represents nothing.
Array	[1, 2, 3]	A collection of values.
Object	{ name: ""John"", age: 30 }	A collection of key-value pairs.

Strings

Syntax	Description
""hello""	A double-quoted string.
'hello'	A single-quoted string.
|	A literal block scalar.
>	A folded block scalar.
&	An anchor.
*	An alias.

Numbers

Syntax	Description
42	An integer.
3.14	A floating-point number.
0b1010	A binary number.
0o644	An octal number.
0xFF	A hexadecimal number.

Booleans and Null

Syntax	Description
true	A boolean value that represents true.
false	A boolean value that represents false.
null	A value that represents nothing.

Arrays

Syntax	Description
[1, 2, 3]	An array of integers.
[""apple"", ""banana"", ""cherry""]	An array of strings.
[true, false, null]	An array of booleans and null.
- item1 - item2 - item3	An array of items.

Objects

Syntax	Description
{ name: ""John"", age: 30 }	An object with two key-value pairs.
{}	An empty object.
key: value key2: value2	An object with multiple key-value pairs.

Advanced Features

Syntax	Description
!	A tag.
<<	A merge key.
&	An anchor.
*	An alias.
>	A folded block scalar.
|	A literal block scalar.

References

• YAML Specification
• YAML Tutorial