Generator Block

The generator block tells baml-cli generate how to generate code for your target language. You can define multiple generators to output code for different languages.

tip

If you created your project using baml-cli init, a generator has already been created for you.

Syntax

generator target {
    output_type "<language>"
    output_dir "<path>"
    version "<version>"
    // language-specific options...
}

Language Examples

Python

generator target {
    output_type "python/pydantic"

    // Where the generated code will be saved (relative to baml_src/)
    output_dir "../"

    // What interface to export at top level (sync/async)
    // Both are generated regardless
    default_client_mode "sync"

    // Version of runtime (should match installed baml-py version)
    version "0.76.2"
}

Python (Pydantic 1.x)

generator target {
    // Compatible with Pydantic 1.x
    output_type "python/pydantic/v1"

    output_dir "../"
    default_client_mode "sync"
    version "0.76.2"

    // Optional: run formatters after generating
    on_generate "black . && isort ."
}

TypeScript

generator target {
    output_type "typescript"

    output_dir "../"
    default_client_mode "async"

    // Version (should match @boundaryml/baml package)
    version "0.76.2"

    // Module format: "esm" or "cjs" (default)
    module_format "cjs"
}

React/Next.js

generator target {
    output_type "typescript/react"

    output_dir "../"
    default_client_mode "async"
    version "0.76.2"
    module_format "cjs"

    // Optional: run formatters after generating
    on_generate "prettier . --write"
}

Go

generator target {
    output_type "go"

    output_dir "../"

    // Version (should match github.com/boundaryml/baml)
    version "0.205.0"

    // Go module name for the generated client
    client_package_name "example.com/myproject"

    // Required for proper formatting
    on_generate "gofmt -w . && goimports -w . && go mod tidy"
}

Ruby (beta)

generator target {
    output_type "ruby/sorbet"

    output_dir "../"

    // Version (should match installed baml gem)
    version "0.76.2"
}

OpenAPI

generator target {
    output_type "rest/openapi"

    output_dir "../"
    version "0.76.2"

    // Run after generating openapi.yaml
    on_generate "npx @openapitools/openapi-generator-cli generate -i openapi.yaml -g OPENAPI_CLIENT_TYPE -o ."
}

Options

Option	Type	Required	Description
output_type	string	Yes	Target language/framework
output_dir	string	Yes	Output path (relative to baml_src/)
version	string	Yes	Runtime version to target
default_client_mode	"sync" | "async"	No	Default export mode
module_format	"esm" | "cjs"	No	TypeScript module format
client_package_name	string	No	Go module name
on_generate	string	No	Command to run after generation

Output Types

Type	Description
python/pydantic	Python with Pydantic 2.x
python/pydantic/v1	Python with Pydantic 1.x
typescript	TypeScript
typescript/react	TypeScript with React hooks
go	Go
ruby/sorbet	Ruby with Sorbet types (beta)
rest/openapi	OpenAPI specification

See Also

• baml-cli generate - Generate client code
• baml-cli init - Initialize a new project