array (list)

Allow you to store and manipulate collections of data. They can be declared in a concise and readable manner, supporting both single-line and multi-line formats.

Syntax

To declare an array in a BAML file, you can use the following syntax:

1 {
2   key1 [value1, value2, value3],
3   key2 [
4     value1,
5     value2,
6     value3
7   ],
8   key3 [
9     {
10       subkey1 "valueA",
11       subkey2 "valueB"
12     },
13     {
14       subkey1 "valueC",
15       subkey2 "valueD"
16     }
17   ]
18 }

Key Points:

Commas: Optional for multi-line arrays, but recommended for clarity.
Nested Arrays: Supported, allowing complex data structures.
Key-Value Pairs: Arrays can contain objects with key-value pairs.

Usage Examples

Example 1: Simple Array

1 function DescriptionGame(items: string[]) -> string {
2     client "openai/gpt-5-mini"
3     prompt #"
4         What 3 words best describe all of these: {{ items }}.
5     "#
6 }
7 
8 test FruitList {
9     functions [DescriptionGame]
10     args { items ["apple", "banana", "cherry"] }
11 }

Example 2: Multi-line Array

1 test CityDescription {
2     functions [DescriptionGame]
3     args { items [
4             "New York",
5             "Los Angeles",
6             "Chicago"
7         ]
8     }
9 }

1	{
2	key1 [value1, value2, value3],
3	key2 [
4	value1,
5	value2,
6	value3
7	],
8	key3 [
9	{
10	subkey1 "valueA",
11	subkey2 "valueB"
12	},
13	{
14	subkey1 "valueC",
15	subkey2 "valueD"
16	}
17	]
18	}

1	function DescriptionGame(items: string[]) -> string {
2	client "openai/gpt-5-mini"
3	prompt #"
4	What 3 words best describe all of these: {{ items }}.
5	"#
6	}
7
8	test FruitList {
9	functions [DescriptionGame]
10	args { items ["apple", "banana", "cherry"] }
11	}

1	test CityDescription {
2	functions [DescriptionGame]
3	args { items [
4	"New York",
5	"Los Angeles",
6	"Chicago"
7	]
8	}
9	}