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Arrays

Arrays store ordered collections of elements of the same type.

Syntax​

Type[]

Examples​

Type Declaration​

string[]           // array of strings
int[]              // array of integers
MyClass[]          // array of custom class
(int | string)[]   // array of union type
int[][]            // nested array (2D)

In Functions​

function DescriptionGame(items: string[]) -> string {
    client "openai/gpt-4o-mini"
    prompt #"
        What 3 words best describe all of these: {{ items }}.
    "#
}

In Tests​

Single-line format:

test FruitList {
    functions [DescriptionGame]
    args { items ["apple", "banana", "cherry"] }
}

Multi-line format:

test CityDescription {
    functions [DescriptionGame]
    args {
        items [
            "New York",
            "Los Angeles",
            "Chicago"
        ]
    }
}

Nested Arrays​

Arrays can contain objects with key-value pairs:

{
  key1 [value1, value2, value3],
  key2 [
    value1,
    value2,
    value3
  ],
  key3 [
    {
      subkey1 "valueA",
      subkey2 "valueB"
    },
    {
      subkey1 "valueC",
      subkey2 "valueD"
    }
  ]
}

Key Points​

  • Commas are optional in multi-line arrays but recommended for clarity
  • Nested arrays are supported for complex data structures
  • Arrays can contain objects with key-value pairs
  • Array types can be nested to create multi-dimensional arrays
  • An array type cannot be optional (use Type[]? is invalid, use Type[] with empty array instead)

Language Equivalents​

BAMLPythonTypeScriptGo
string[]List[str]string[][]string
int[]List[int]number[][]int
(int | float)[]List[Union[int, float]]number[][]Union2IntOrFloat

See Also​