langchain_core.runnables.base.RunnableLambda

class langchain_core.runnables.base.RunnableLambda(func: Union[Union[Callable[[Input], Output], Callable[[Input, RunnableConfig], Output], Callable[[Input, CallbackManagerForChainRun], Output], Callable[[Input, CallbackManagerForChainRun, RunnableConfig], Output]], Union[Callable[[Input], Awaitable[Output]], Callable[[Input, RunnableConfig], Awaitable[Output]], Callable[[Input, AsyncCallbackManagerForChainRun], Awaitable[Output]], Callable[[Input, AsyncCallbackManagerForChainRun, RunnableConfig], Awaitable[Output]]]], afunc: Optional[Union[Callable[[Input], Awaitable[Output]], Callable[[Input, RunnableConfig], Awaitable[Output]], Callable[[Input, AsyncCallbackManagerForChainRun], Awaitable[Output]], Callable[[Input, AsyncCallbackManagerForChainRun, RunnableConfig], Awaitable[Output]]]] = None)

RunnableLambda converts a python callable into a Runnable.

Wrapping a callable in a RunnableLambda makes the callable usable within either a sync or async context.

RunnableLambda can be composed as any other Runnable and provides seamless integration with LangChain tracing.

Examples

# This is a RunnableLambda
from langchain_core.runnables import RunnableLambda

def add_one(x: int) -> int:
    return x + 1

runnable = RunnableLambda(add_one)

runnable.invoke(1) # returns 2
runnable.batch([1, 2, 3]) # returns [2, 3, 4]

# Async is supported by default by delegating to the sync implementation
await runnable.ainvoke(1) # returns 2
await runnable.abatch([1, 2, 3]) # returns [2, 3, 4]


# Alternatively, can provide both synd and sync implementations
async def add_one_async(x: int) -> int:
    return x + 1

runnable = RunnableLambda(add_one, afunc=add_one_async)
runnable.invoke(1) # Uses add_one
await runnable.ainvoke(1) # Uses add_one_async

Create a RunnableLambda from a callable, and async callable or both.

Accepts both sync and async variants to allow providing efficient implementations for sync and async execution.

Parameters

• func – Either sync or async callable

• afunc – An async callable that takes an input and returns an output.

Attributes

InputType	The type of the input to this runnable.
OutputType	The type of the output of this runnable as a type annotation.
config_specs	List configurable fields for this runnable.
input_schema	The type of input this runnable accepts specified as a pydantic model.
output_schema	The type of output this runnable produces specified as a pydantic model.

Methods

__init__(func[, afunc])	Create a RunnableLambda from a callable, and async callable or both.
abatch(inputs[, config, return_exceptions])	Default implementation runs ainvoke in parallel using asyncio.gather.
ainvoke(input[, config])	Invoke this runnable asynchronously.
astream(input[, config])	Default implementation of astream, which calls ainvoke.
astream_log(input[, config, diff, ...])	Stream all output from a runnable, as reported to the callback system.
atransform(input[, config])	Default implementation of atransform, which buffers input and calls astream.
batch(inputs[, config, return_exceptions])	Default implementation runs invoke in parallel using a thread pool executor.
bind(**kwargs)	Bind arguments to a Runnable, returning a new Runnable.
config_schema(*[, include])	The type of config this runnable accepts specified as a pydantic model.
get_input_schema([config])	The pydantic schema for the input to this runnable.
get_output_schema([config])	Get a pydantic model that can be used to validate output to the runnable.
invoke(input[, config])	Invoke this runnable synchronously.
map()	Return a new Runnable that maps a list of inputs to a list of outputs, by calling invoke() with each input.
stream(input[, config])	Default implementation of stream, which calls invoke.
transform(input[, config])	Default implementation of transform, which buffers input and then calls stream.
with_config([config])	Bind config to a Runnable, returning a new Runnable.
with_fallbacks(fallbacks, *[, ...])	Add fallbacks to a runnable, returning a new Runnable.
with_listeners(*[, on_start, on_end, on_error])	Bind lifecycle listeners to a Runnable, returning a new Runnable.
with_retry(*[, retry_if_exception_type, ...])	Create a new Runnable that retries the original runnable on exceptions.
with_types(*[, input_type, output_type])	Bind input and output types to a Runnable, returning a new Runnable.

__init__(func: Union[Union[Callable[[Input], Output], Callable[[Input, RunnableConfig], Output], Callable[[Input, CallbackManagerForChainRun], Output], Callable[[Input, CallbackManagerForChainRun, RunnableConfig], Output]], Union[Callable[[Input], Awaitable[Output]], Callable[[Input, RunnableConfig], Awaitable[Output]], Callable[[Input, AsyncCallbackManagerForChainRun], Awaitable[Output]], Callable[[Input, AsyncCallbackManagerForChainRun, RunnableConfig], Awaitable[Output]]]], afunc: Optional[Union[Callable[[Input], Awaitable[Output]], Callable[[Input, RunnableConfig], Awaitable[Output]], Callable[[Input, AsyncCallbackManagerForChainRun], Awaitable[Output]], Callable[[Input, AsyncCallbackManagerForChainRun, RunnableConfig], Awaitable[Output]]]] = None) → None

Create a RunnableLambda from a callable, and async callable or both.

Accepts both sync and async variants to allow providing efficient implementations for sync and async execution.

Parameters

• func – Either sync or async callable

• afunc – An async callable that takes an input and returns an output.

async abatch(inputs: List[Input], config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None, *, return_exceptions: bool = False, **kwargs: Optional[Any]) → List[Output]

Default implementation runs ainvoke in parallel using asyncio.gather.

The default implementation of batch works well for IO bound runnables.

Subclasses should override this method if they can batch more efficiently; e.g., if the underlying runnable uses an API which supports a batch mode.

async ainvoke(input: Input, config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → Output

Invoke this runnable asynchronously.

async astream(input: Input, config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → AsyncIterator[Output]

Default implementation of astream, which calls ainvoke. Subclasses should override this method if they support streaming output.

async astream_log(input: Any, config: Optional[RunnableConfig] = None, *, diff: bool = True, with_streamed_output_list: bool = True, include_names: Optional[Sequence[str]] = None, include_types: Optional[Sequence[str]] = None, include_tags: Optional[Sequence[str]] = None, exclude_names: Optional[Sequence[str]] = None, exclude_types: Optional[Sequence[str]] = None, exclude_tags: Optional[Sequence[str]] = None, **kwargs: Optional[Any]) → Union[AsyncIterator[RunLogPatch], AsyncIterator[RunLog]]

Stream all output from a runnable, as reported to the callback system. This includes all inner runs of LLMs, Retrievers, Tools, etc.

Output is streamed as Log objects, which include a list of jsonpatch ops that describe how the state of the run has changed in each step, and the final state of the run.

The jsonpatch ops can be applied in order to construct state.

Parameters

• input – The input to the runnable.

• config – The config to use for the runnable.

• diff – Whether to yield diffs between each step, or the current state.

• with_streamed_output_list – Whether to yield the streamed_output list.

• include_names – Only include logs with these names.

• include_types – Only include logs with these types.

• include_tags – Only include logs with these tags.

• exclude_names – Exclude logs with these names.

• exclude_types – Exclude logs with these types.

• exclude_tags – Exclude logs with these tags.

async atransform(input: AsyncIterator[Input], config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → AsyncIterator[Output]

Default implementation of atransform, which buffers input and calls astream. Subclasses should override this method if they can start producing output while input is still being generated.

batch(inputs: List[Input], config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None, *, return_exceptions: bool = False, **kwargs: Optional[Any]) → List[Output]

Default implementation runs invoke in parallel using a thread pool executor.

The default implementation of batch works well for IO bound runnables.

Subclasses should override this method if they can batch more efficiently; e.g., if the underlying runnable uses an API which supports a batch mode.

bind(**kwargs: Any) → Runnable[Input, Output]

Bind arguments to a Runnable, returning a new Runnable.

config_schema(*, include: Optional[Sequence[str]] = None) → Type[BaseModel]

The type of config this runnable accepts specified as a pydantic model.

To mark a field as configurable, see the configurable_fields and configurable_alternatives methods.

Parameters

include – A list of fields to include in the config schema.

Returns

A pydantic model that can be used to validate config.

get_input_schema(config: Optional[RunnableConfig] = None) → Type[BaseModel]

The pydantic schema for the input to this runnable.

get_output_schema(config: Optional[RunnableConfig] = None) → Type[BaseModel]

Get a pydantic model that can be used to validate output to the runnable.

Runnables that leverage the configurable_fields and configurable_alternatives methods will have a dynamic output schema that depends on which configuration the runnable is invoked with.

This method allows to get an output schema for a specific configuration.

Parameters

config – A config to use when generating the schema.

Returns

A pydantic model that can be used to validate output.

invoke(input: Input, config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → Output

Invoke this runnable synchronously.

map() → Runnable[List[Input], List[Output]]

Return a new Runnable that maps a list of inputs to a list of outputs, by calling invoke() with each input.

stream(input: Input, config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → Iterator[Output]

Default implementation of stream, which calls invoke. Subclasses should override this method if they support streaming output.

transform(input: Iterator[Input], config: Optional[RunnableConfig] = None, **kwargs: Optional[Any]) → Iterator[Output]

Default implementation of transform, which buffers input and then calls stream. Subclasses should override this method if they can start producing output while input is still being generated.

with_config(config: Optional[RunnableConfig] = None, **kwargs: Any) → Runnable[Input, Output]

Bind config to a Runnable, returning a new Runnable.

with_fallbacks(fallbacks: Sequence[Runnable[Input, Output]], *, exceptions_to_handle: Tuple[Type[BaseException], ...] = (<class 'Exception'>,)) → RunnableWithFallbacksT[Input, Output]

Add fallbacks to a runnable, returning a new Runnable.

Parameters

• fallbacks – A sequence of runnables to try if the original runnable fails.

• exceptions_to_handle – A tuple of exception types to handle.

Returns

A new Runnable that will try the original runnable, and then each fallback in order, upon failures.

with_listeners(*, on_start: Optional[Listener] = None, on_end: Optional[Listener] = None, on_error: Optional[Listener] = None) → Runnable[Input, Output]

Bind lifecycle listeners to a Runnable, returning a new Runnable.

on_start: Called before the runnable starts running, with the Run object. on_end: Called after the runnable finishes running, with the Run object. on_error: Called if the runnable throws an error, with the Run object.

The Run object contains information about the run, including its id, type, input, output, error, start_time, end_time, and any tags or metadata added to the run.

with_retry(*, retry_if_exception_type: ~typing.Tuple[~typing.Type[BaseException], ...] = (<class 'Exception'>,), wait_exponential_jitter: bool = True, stop_after_attempt: int = 3) → Runnable[Input, Output]

Create a new Runnable that retries the original runnable on exceptions.

Parameters

• retry_if_exception_type – A tuple of exception types to retry on

• wait_exponential_jitter – Whether to add jitter to the wait time between retries

• stop_after_attempt – The maximum number of attempts to make before giving up

Returns

A new Runnable that retries the original runnable on exceptions.

with_types(*, input_type: Optional[Type[Input]] = None, output_type: Optional[Type[Output]] = None) → Runnable[Input, Output]

Bind input and output types to a Runnable, returning a new Runnable.

Examples using RunnableLambda

• sql_db.md

• Run arbitrary functions