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Maps

Maps (dictionaries) store key-value pairs.

Syntax​

map<KeyType, ValueType>

Supported Key Types​

  • string
  • enum values
  • Literal strings ("A" | "B" | "C")

Examples​

Basic Map​

map<string, string>
map<string, int>
map<string, MyClass>

Enum Keys​

enum Category {
  A
  B
  C
}

map<Category, string>

Literal String Keys​

map<"A" | "B" | "C", string>

Usage Examples​

Simple Map​

class Person {
    name string
    age int
    isEmployed bool
}

function DescribePerson(person: Person) -> string {
    client "openai/gpt-4o-mini"
    prompt #"
        Describe the person: {{ person }}.
    "#
}

test PersonDescription {
    functions [DescribePerson]
    args {
        person {
            name "John Doe",
            age 30,
            isEmployed true
        }
    }
}

Nested Map​

class Company {
    name string
    location map<string, string>
    employeeCount int
}

function DescribeCompany(company: Company) -> string {
    client "openai/gpt-4o-mini"
    prompt #"
        Describe the company: {{ company }}.
    "#
}

test CompanyDescription {
    functions [DescribeCompany]
    args {
        company {
            name "TechCorp",
            location {
                city "San Francisco",
                state "California"
            },
            employeeCount 500
        }
    }
}

Map with Multiline String​

class Project {
    title string
    description string
}

test ProjectDescription {
    functions [DescribeProject]
    args {
        project {
            title "AI Research",
            description #"
                This project focuses on developing
                advanced AI algorithms to improve
                machine learning capabilities.
            "#
        }
    }
}

Key Points​

  • Keys and values are separated by spaces (no colons)
  • Maps can contain unquoted or quoted strings, booleans, numbers, and nested maps
  • Classes in BAML are represented as maps with keys and values
  • Most of BAML (clients, tests, classes, etc.) is represented as a map

See Also​