from __future__ import annotations
import asyncio
import collections
import inspect
import threading
from abc import ABC, abstractmethod
from concurrent.futures import FIRST_COMPLETED, wait
from contextvars import copy_context
from copy import deepcopy
from functools import wraps
from itertools import groupby, tee
from operator import itemgetter
from typing import (
TYPE_CHECKING,
Any,
AsyncIterator,
Awaitable,
Callable,
Coroutine,
Dict,
Generic,
Iterator,
List,
Mapping,
Optional,
Sequence,
Set,
Tuple,
Type,
TypeVar,
Union,
cast,
overload,
)
from typing_extensions import Literal, get_args
from langchain_core.load.dump import dumpd, dumps
from langchain_core.load.serializable import Serializable
from langchain_core.pydantic_v1 import BaseConfig, BaseModel, Field, create_model
from langchain_core.runnables.config import (
RunnableConfig,
acall_func_with_variable_args,
call_func_with_variable_args,
ensure_config,
get_async_callback_manager_for_config,
get_callback_manager_for_config,
get_config_list,
get_executor_for_config,
merge_configs,
patch_config,
run_in_executor,
var_child_runnable_config,
)
from langchain_core.runnables.graph import Graph
from langchain_core.runnables.utils import (
AddableDict,
AnyConfigurableField,
ConfigurableField,
ConfigurableFieldSpec,
Input,
Output,
accepts_config,
accepts_context,
accepts_run_manager,
gather_with_concurrency,
get_function_first_arg_dict_keys,
get_function_nonlocals,
get_lambda_source,
get_unique_config_specs,
indent_lines_after_first,
)
from langchain_core.utils.aiter import atee, py_anext
from langchain_core.utils.iter import safetee
if TYPE_CHECKING:
from langchain_core.callbacks.manager import (
AsyncCallbackManagerForChainRun,
CallbackManagerForChainRun,
)
from langchain_core.prompts.base import BasePromptTemplate
from langchain_core.runnables.fallbacks import (
RunnableWithFallbacks as RunnableWithFallbacksT,
)
from langchain_core.tracers.log_stream import RunLog, RunLogPatch
from langchain_core.tracers.root_listeners import Listener
Other = TypeVar("Other")
class _SchemaConfig(BaseConfig):
arbitrary_types_allowed = True
[docs]class Runnable(Generic[Input, Output], ABC):
"""A unit of work that can be invoked, batched, streamed, transformed and composed.
Key Methods
===========
* invoke/ainvoke: Transforms a single input into an output.
* batch/abatch: Efficiently transforms multiple inputs into outputs.
* stream/astream: Streams output from a single input as it's produced.
* astream_log: Streams output and selected intermediate results from an input.
Built-in optimizations:
* Batch: By default, batch runs invoke() in parallel using a thread pool executor.
Override to optimize batching.
* Async: Methods with "a" suffix are asynchronous. By default, they execute
the sync counterpart using asyncio's thread pool.
Override for native async.
All methods accept an optional config argument, which can be used to configure
execution, add tags and metadata for tracing and debugging etc.
Runnables expose schematic information about their input, output and config via
the input_schema property, the output_schema property and config_schema method.
LCEL and Composition
====================
The LangChain Expression Language (LCEL) is a declarative way to compose Runnables
into chains. Any chain constructed this way will automatically have sync, async,
batch, and streaming support.
The main composition primitives are RunnableSequence and RunnableParallel.
RunnableSequence invokes a series of runnables sequentially, with one runnable's
output serving as the next's input. Construct using the `|` operator or by
passing a list of runnables to RunnableSequence.
RunnableParallel invokes runnables concurrently, providing the same input
to each. Construct it using a dict literal within a sequence or by passing a
dict to RunnableParallel.
For example,
.. code-block:: python
from langchain_core.runnables import RunnableLambda
# A RunnableSequence constructed using the `|` operator
sequence = RunnableLambda(lambda x: x + 1) | RunnableLambda(lambda x: x * 2)
sequence.invoke(1) # 4
sequence.batch([1, 2, 3]) # [4, 6, 8]
# A sequence that contains a RunnableParallel constructed using a dict literal
sequence = RunnableLambda(lambda x: x + 1) | {
'mul_2': RunnableLambda(lambda x: x * 2),
'mul_5': RunnableLambda(lambda x: x * 5)
}
sequence.invoke(1) # {'mul_2': 4, 'mul_5': 10}
Standard Methods
================
All Runnables expose additional methods that can be used to modify their behavior
(e.g., add a retry policy, add lifecycle listeners, make them configurable, etc.).
These methods will work on any Runnable, including Runnable chains constructed
by composing other Runnables. See the individual methods for details.
For example,
.. code-block:: python
from langchain_core.runnables import RunnableLambda
import random
def add_one(x: int) -> int:
return x + 1
def buggy_double(y: int) -> int:
'''Buggy code that will fail 70% of the time'''
if random.random() > 0.3:
print('This code failed, and will probably be retried!')
raise ValueError('Triggered buggy code')
return y * 2
sequence = (
RunnableLambda(add_one) |
RunnableLambda(buggy_double).with_retry( # Retry on failure
stop_after_attempt=10,
wait_exponential_jitter=False
)
)
print(sequence.input_schema.schema()) # Show inferred input schema
print(sequence.output_schema.schema()) # Show inferred output schema
print(sequence.invoke(2)) # invoke the sequence (note the retry above!!)
Debugging and tracing
=====================
As the chains get longer, it can be useful to be able to see intermediate results
to debug and trace the chain.
You can set the global debug flag to True to enable debug output for all chains:
.. code-block:: python
from langchain_core.globals import set_debug
set_debug(True)
Alternatively, you can pass existing or custom callbacks to any given chain:
.. code-block:: python
from langchain_core.tracers import ConsoleCallbackHandler
chain.invoke(
...,
config={'callbacks': [ConsoleCallbackHandler()]}
)
For a UI (and much more) checkout LangSmith: https://docs.smith.langchain.com/
"""
name: Optional[str] = None
"""The name of the runnable. Used for debugging and tracing."""
[docs] def get_name(
self, suffix: Optional[str] = None, *, name: Optional[str] = None
) -> str:
"""Get the name of the runnable."""
name = name or self.name or self.__class__.__name__
if suffix:
if name[0].isupper():
return name + suffix.title()
else:
return name + "_" + suffix.lower()
else:
return name
@property
def InputType(self) -> Type[Input]:
"""The type of input this runnable accepts specified as a type annotation."""
for cls in self.__class__.__orig_bases__: # type: ignore[attr-defined]
type_args = get_args(cls)
if type_args and len(type_args) == 2:
return type_args[0]
raise TypeError(
f"Runnable {self.get_name()} doesn't have an inferable InputType. "
"Override the InputType property to specify the input type."
)
@property
def OutputType(self) -> Type[Output]:
"""The type of output this runnable produces specified as a type annotation."""
for cls in self.__class__.__orig_bases__: # type: ignore[attr-defined]
type_args = get_args(cls)
if type_args and len(type_args) == 2:
return type_args[1]
raise TypeError(
f"Runnable {self.get_name()} doesn't have an inferable OutputType. "
"Override the OutputType property to specify the output type."
)
@property
def input_schema(self) -> Type[BaseModel]:
"""The type of input this runnable accepts specified as a pydantic model."""
return self.get_input_schema()
@property
def output_schema(self) -> Type[BaseModel]:
"""The type of output this runnable produces specified as a pydantic model."""
return self.get_output_schema()
[docs] def get_output_schema(
self, 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.
Args:
config: A config to use when generating the schema.
Returns:
A pydantic model that can be used to validate output.
"""
root_type = self.OutputType
if inspect.isclass(root_type) and issubclass(root_type, BaseModel):
return root_type
return create_model(
self.get_name("Output"),
__root__=(root_type, None),
__config__=_SchemaConfig,
)
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
"""List configurable fields for this runnable."""
return []
[docs] def config_schema(
self, *, 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.
Args:
include: A list of fields to include in the config schema.
Returns:
A pydantic model that can be used to validate config.
"""
include = include or []
config_specs = self.config_specs
configurable = (
create_model( # type: ignore[call-overload]
"Configurable",
**{
spec.id: (
spec.annotation,
Field(
spec.default, title=spec.name, description=spec.description
),
)
for spec in config_specs
},
__config__=_SchemaConfig,
)
if config_specs
else None
)
return create_model( # type: ignore[call-overload]
self.get_name("Config"),
__config__=_SchemaConfig,
**({"configurable": (configurable, None)} if configurable else {}),
**{
field_name: (field_type, None)
for field_name, field_type in RunnableConfig.__annotations__.items()
if field_name in [i for i in include if i != "configurable"]
},
)
[docs] def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
"""Return a graph representation of this runnable."""
from langchain_core.runnables.graph import Graph
graph = Graph()
input_node = graph.add_node(self.get_input_schema(config))
runnable_node = graph.add_node(self)
output_node = graph.add_node(self.get_output_schema(config))
graph.add_edge(input_node, runnable_node)
graph.add_edge(runnable_node, output_node)
return graph
[docs] def get_prompts(
self, config: Optional[RunnableConfig] = None
) -> List[BasePromptTemplate]:
from langchain_core.prompts.base import BasePromptTemplate
prompts = []
for _, node in self.get_graph(config=config).nodes.items():
if isinstance(node.data, BasePromptTemplate):
prompts.append(node.data)
return prompts
def __or__(
self,
other: Union[
Runnable[Any, Other],
Callable[[Any], Other],
Callable[[Iterator[Any]], Iterator[Other]],
Mapping[str, Union[Runnable[Any, Other], Callable[[Any], Other], Any]],
],
) -> RunnableSerializable[Input, Other]:
"""Compose this runnable with another object to create a RunnableSequence."""
return RunnableSequence(self, coerce_to_runnable(other))
def __ror__(
self,
other: Union[
Runnable[Other, Any],
Callable[[Other], Any],
Callable[[Iterator[Other]], Iterator[Any]],
Mapping[str, Union[Runnable[Other, Any], Callable[[Other], Any], Any]],
],
) -> RunnableSerializable[Other, Output]:
"""Compose this runnable with another object to create a RunnableSequence."""
return RunnableSequence(coerce_to_runnable(other), self)
[docs] def pipe(
self,
*others: Union[Runnable[Any, Other], Callable[[Any], Other]],
name: Optional[str] = None,
) -> RunnableSerializable[Input, Other]:
"""Compose this runnable with another object to create a RunnableSequence."""
return RunnableSequence(self, *others, name=name)
[docs] def pick(self, keys: Union[str, List[str]]) -> RunnableSerializable[Any, Any]:
"""Pick keys from the dict output of this runnable.
Returns a new runnable."""
from langchain_core.runnables.passthrough import RunnablePick
return self | RunnablePick(keys)
[docs] def assign(
self,
**kwargs: Union[
Runnable[Dict[str, Any], Any],
Callable[[Dict[str, Any]], Any],
Mapping[
str,
Union[Runnable[Dict[str, Any], Any], Callable[[Dict[str, Any]], Any]],
],
],
) -> RunnableSerializable[Any, Any]:
"""Assigns new fields to the dict output of this runnable.
Returns a new runnable."""
from langchain_core.runnables.passthrough import RunnableAssign
return self | RunnableAssign(RunnableParallel(kwargs))
""" --- Public API --- """
[docs] @abstractmethod
def invoke(self, input: Input, config: Optional[RunnableConfig] = None) -> Output:
"""Transform a single input into an output. Override to implement.
Args:
input: The input to the runnable.
config: A config to use when invoking the runnable.
The config supports standard keys like 'tags', 'metadata' for tracing
purposes, 'max_concurrency' for controlling how much work to do
in parallel, and other keys. Please refer to the RunnableConfig
for more details.
Returns:
The output of the runnable.
"""
[docs] async def ainvoke(
self, input: Input, config: Optional[RunnableConfig] = None, **kwargs: Any
) -> Output:
"""Default implementation of ainvoke, calls invoke from a thread.
The default implementation allows usage of async code even if
the runnable did not implement a native async version of invoke.
Subclasses should override this method if they can run asynchronously.
"""
return await run_in_executor(config, self.invoke, input, config, **kwargs)
[docs] def batch(
self,
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.
"""
if not inputs:
return []
configs = get_config_list(config, len(inputs))
def invoke(input: Input, config: RunnableConfig) -> Union[Output, Exception]:
if return_exceptions:
try:
return self.invoke(input, config, **kwargs)
except Exception as e:
return e
else:
return self.invoke(input, config, **kwargs)
# If there's only one input, don't bother with the executor
if len(inputs) == 1:
return cast(List[Output], [invoke(inputs[0], configs[0])])
with get_executor_for_config(configs[0]) as executor:
return cast(List[Output], list(executor.map(invoke, inputs, configs)))
[docs] async def abatch(
self,
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.
"""
if not inputs:
return []
configs = get_config_list(config, len(inputs))
async def ainvoke(
input: Input, config: RunnableConfig
) -> Union[Output, Exception]:
if return_exceptions:
try:
return await self.ainvoke(input, config, **kwargs)
except Exception as e:
return e
else:
return await self.ainvoke(input, config, **kwargs)
coros = map(ainvoke, inputs, configs)
return await gather_with_concurrency(configs[0].get("max_concurrency"), *coros)
[docs] def stream(
self,
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.
"""
yield self.invoke(input, config, **kwargs)
[docs] async def astream(
self,
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.
"""
yield await self.ainvoke(input, config, **kwargs)
@overload
def astream_log(
self,
input: Any,
config: Optional[RunnableConfig] = None,
*,
diff: Literal[True] = 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],
) -> AsyncIterator[RunLogPatch]:
...
@overload
def astream_log(
self,
input: Any,
config: Optional[RunnableConfig] = None,
*,
diff: Literal[False],
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],
) -> AsyncIterator[RunLog]:
...
[docs] async def astream_log(
self,
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.
Args:
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.
"""
import jsonpatch # type: ignore[import]
from langchain_core.callbacks.base import BaseCallbackManager
from langchain_core.tracers.log_stream import (
LogStreamCallbackHandler,
RunLog,
RunLogPatch,
)
# Create a stream handler that will emit Log objects
stream = LogStreamCallbackHandler(
auto_close=False,
include_names=include_names,
include_types=include_types,
include_tags=include_tags,
exclude_names=exclude_names,
exclude_types=exclude_types,
exclude_tags=exclude_tags,
)
# Assign the stream handler to the config
config = ensure_config(config)
callbacks = config.get("callbacks")
if callbacks is None:
config["callbacks"] = [stream]
elif isinstance(callbacks, list):
config["callbacks"] = callbacks + [stream]
elif isinstance(callbacks, BaseCallbackManager):
callbacks = callbacks.copy()
callbacks.add_handler(stream, inherit=True)
config["callbacks"] = callbacks
else:
raise ValueError(
f"Unexpected type for callbacks: {callbacks}."
"Expected None, list or AsyncCallbackManager."
)
# Call the runnable in streaming mode,
# add each chunk to the output stream
async def consume_astream() -> None:
try:
prev_final_output: Optional[Output] = None
final_output: Optional[Output] = None
async for chunk in self.astream(input, config, **kwargs):
prev_final_output = final_output
if final_output is None:
final_output = chunk
else:
try:
final_output = final_output + chunk # type: ignore
except TypeError:
final_output = chunk
patches: List[Dict[str, Any]] = []
if with_streamed_output_list:
patches.append(
{
"op": "add",
"path": "/streamed_output/-",
# chunk cannot be shared between
# streamed_output and final_output
# otherwise jsonpatch.apply will
# modify both
"value": deepcopy(chunk),
}
)
for op in jsonpatch.JsonPatch.from_diff(
prev_final_output, final_output, dumps=dumps
):
patches.append({**op, "path": f"/final_output{op['path']}"})
await stream.send_stream.send(RunLogPatch(*patches))
finally:
await stream.send_stream.aclose()
# Start the runnable in a task, so we can start consuming output
task = asyncio.create_task(consume_astream())
try:
# Yield each chunk from the output stream
if diff:
async for log in stream:
yield log
else:
state = RunLog(state=None) # type: ignore[arg-type]
async for log in stream:
state = state + log
yield state
finally:
# Wait for the runnable to finish, if not cancelled (eg. by break)
try:
await task
except asyncio.CancelledError:
pass
[docs] def bind(self, **kwargs: Any) -> Runnable[Input, Output]:
"""
Bind arguments to a Runnable, returning a new Runnable.
"""
return RunnableBinding(bound=self, kwargs=kwargs, config={})
[docs] def with_config(
self,
config: Optional[RunnableConfig] = None,
# Sadly Unpack is not well supported by mypy so this will have to be untyped
**kwargs: Any,
) -> Runnable[Input, Output]:
"""
Bind config to a Runnable, returning a new Runnable.
"""
return RunnableBinding(
bound=self,
config=cast(
RunnableConfig,
{**(config or {}), **kwargs},
), # type: ignore[misc]
kwargs={},
)
[docs] def with_listeners(
self,
*,
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.
"""
from langchain_core.tracers.root_listeners import RootListenersTracer
return RunnableBinding(
bound=self,
config_factories=[
lambda config: {
"callbacks": [
RootListenersTracer(
config=config,
on_start=on_start,
on_end=on_end,
on_error=on_error,
)
],
}
],
)
[docs] def with_types(
self,
*,
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.
"""
return RunnableBinding(
bound=self,
custom_input_type=input_type,
custom_output_type=output_type,
kwargs={},
)
[docs] def with_retry(
self,
*,
retry_if_exception_type: Tuple[Type[BaseException], ...] = (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.
Args:
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.
"""
from langchain_core.runnables.retry import RunnableRetry
return RunnableRetry(
bound=self,
kwargs={},
config={},
retry_exception_types=retry_if_exception_type,
wait_exponential_jitter=wait_exponential_jitter,
max_attempt_number=stop_after_attempt,
)
[docs] def map(self) -> 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.
"""
return RunnableEach(bound=self)
[docs] def with_fallbacks(
self,
fallbacks: Sequence[Runnable[Input, Output]],
*,
exceptions_to_handle: Tuple[Type[BaseException], ...] = (Exception,),
) -> RunnableWithFallbacksT[Input, Output]:
"""Add fallbacks to a runnable, returning a new Runnable.
Args:
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.
"""
from langchain_core.runnables.fallbacks import RunnableWithFallbacks
return RunnableWithFallbacks(
runnable=self,
fallbacks=fallbacks,
exceptions_to_handle=exceptions_to_handle,
)
""" --- Helper methods for Subclasses --- """
def _call_with_config(
self,
func: Union[
Callable[[Input], Output],
Callable[[Input, CallbackManagerForChainRun], Output],
Callable[[Input, CallbackManagerForChainRun, RunnableConfig], Output],
],
input: Input,
config: Optional[RunnableConfig],
run_type: Optional[str] = None,
**kwargs: Optional[Any],
) -> Output:
"""Helper method to transform an Input value to an Output value,
with callbacks. Use this method to implement invoke() in subclasses."""
config = ensure_config(config)
callback_manager = get_callback_manager_for_config(config)
run_manager = callback_manager.on_chain_start(
dumpd(self),
input,
run_type=run_type,
name=config.get("run_name") or self.get_name(),
)
try:
child_config = patch_config(config, callbacks=run_manager.get_child())
context = copy_context()
context.run(var_child_runnable_config.set, child_config)
output = cast(
Output,
context.run(
call_func_with_variable_args,
func, # type: ignore[arg-type]
input, # type: ignore[arg-type]
config,
run_manager,
**kwargs,
),
)
except BaseException as e:
run_manager.on_chain_error(e)
raise
else:
run_manager.on_chain_end(dumpd(output))
return output
async def _acall_with_config(
self,
func: Union[
Callable[[Input], Awaitable[Output]],
Callable[[Input, AsyncCallbackManagerForChainRun], Awaitable[Output]],
Callable[
[Input, AsyncCallbackManagerForChainRun, RunnableConfig],
Awaitable[Output],
],
],
input: Input,
config: Optional[RunnableConfig],
run_type: Optional[str] = None,
**kwargs: Optional[Any],
) -> Output:
"""Helper method to transform an Input value to an Output value,
with callbacks. Use this method to implement ainvoke() in subclasses."""
config = ensure_config(config)
callback_manager = get_async_callback_manager_for_config(config)
run_manager = await callback_manager.on_chain_start(
dumpd(self),
input,
run_type=run_type,
name=config.get("run_name") or self.get_name(),
)
try:
child_config = patch_config(config, callbacks=run_manager.get_child())
context = copy_context()
context.run(var_child_runnable_config.set, child_config)
coro = acall_func_with_variable_args(
func, input, config, run_manager, **kwargs
)
if accepts_context(asyncio.create_task):
output: Output = await asyncio.create_task(coro, context=context) # type: ignore
else:
output = await coro
except BaseException as e:
await run_manager.on_chain_error(e)
raise
else:
await run_manager.on_chain_end(dumpd(output))
return output
def _batch_with_config(
self,
func: Union[
Callable[[List[Input]], List[Union[Exception, Output]]],
Callable[
[List[Input], List[CallbackManagerForChainRun]],
List[Union[Exception, Output]],
],
Callable[
[List[Input], List[CallbackManagerForChainRun], List[RunnableConfig]],
List[Union[Exception, Output]],
],
],
input: List[Input],
config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
run_type: Optional[str] = None,
**kwargs: Optional[Any],
) -> List[Output]:
"""Helper method to transform an Input value to an Output value,
with callbacks. Use this method to implement invoke() in subclasses."""
if not input:
return []
configs = get_config_list(config, len(input))
callback_managers = [get_callback_manager_for_config(c) for c in configs]
run_managers = [
callback_manager.on_chain_start(
dumpd(self),
input,
run_type=run_type,
name=config.get("run_name") or self.get_name(),
)
for callback_manager, input, config in zip(
callback_managers, input, configs
)
]
try:
if accepts_config(func):
kwargs["config"] = [
patch_config(c, callbacks=rm.get_child())
for c, rm in zip(configs, run_managers)
]
if accepts_run_manager(func):
kwargs["run_manager"] = run_managers
output = func(input, **kwargs) # type: ignore[call-arg]
except BaseException as e:
for run_manager in run_managers:
run_manager.on_chain_error(e)
if return_exceptions:
return cast(List[Output], [e for _ in input])
else:
raise
else:
first_exception: Optional[Exception] = None
for run_manager, out in zip(run_managers, output):
if isinstance(out, Exception):
first_exception = first_exception or out
run_manager.on_chain_error(out)
else:
run_manager.on_chain_end(dumpd(out))
if return_exceptions or first_exception is None:
return cast(List[Output], output)
else:
raise first_exception
async def _abatch_with_config(
self,
func: Union[
Callable[[List[Input]], Awaitable[List[Union[Exception, Output]]]],
Callable[
[List[Input], List[AsyncCallbackManagerForChainRun]],
Awaitable[List[Union[Exception, Output]]],
],
Callable[
[
List[Input],
List[AsyncCallbackManagerForChainRun],
List[RunnableConfig],
],
Awaitable[List[Union[Exception, Output]]],
],
],
input: List[Input],
config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
run_type: Optional[str] = None,
**kwargs: Optional[Any],
) -> List[Output]:
"""Helper method to transform an Input value to an Output value,
with callbacks. Use this method to implement invoke() in subclasses."""
if not input:
return []
configs = get_config_list(config, len(input))
callback_managers = [get_async_callback_manager_for_config(c) for c in configs]
run_managers: List[AsyncCallbackManagerForChainRun] = await asyncio.gather(
*(
callback_manager.on_chain_start(
dumpd(self),
input,
run_type=run_type,
name=config.get("run_name") or self.get_name(),
)
for callback_manager, input, config in zip(
callback_managers, input, configs
)
)
)
try:
if accepts_config(func):
kwargs["config"] = [
patch_config(c, callbacks=rm.get_child())
for c, rm in zip(configs, run_managers)
]
if accepts_run_manager(func):
kwargs["run_manager"] = run_managers
output = await func(input, **kwargs) # type: ignore[call-arg]
except BaseException as e:
await asyncio.gather(
*(run_manager.on_chain_error(e) for run_manager in run_managers)
)
if return_exceptions:
return cast(List[Output], [e for _ in input])
else:
raise
else:
first_exception: Optional[Exception] = None
coros: List[Awaitable[None]] = []
for run_manager, out in zip(run_managers, output):
if isinstance(out, Exception):
first_exception = first_exception or out
coros.append(run_manager.on_chain_error(out))
else:
coros.append(run_manager.on_chain_end(dumpd(out)))
await asyncio.gather(*coros)
if return_exceptions or first_exception is None:
return cast(List[Output], output)
else:
raise first_exception
def _transform_stream_with_config(
self,
input: Iterator[Input],
transformer: Union[
Callable[[Iterator[Input]], Iterator[Output]],
Callable[[Iterator[Input], CallbackManagerForChainRun], Iterator[Output]],
Callable[
[
Iterator[Input],
CallbackManagerForChainRun,
RunnableConfig,
],
Iterator[Output],
],
],
config: Optional[RunnableConfig],
run_type: Optional[str] = None,
**kwargs: Optional[Any],
) -> Iterator[Output]:
"""Helper method to transform an Iterator of Input values into an Iterator of
Output values, with callbacks.
Use this to implement `stream()` or `transform()` in Runnable subclasses."""
# tee the input so we can iterate over it twice
input_for_tracing, input_for_transform = tee(input, 2)
# Start the input iterator to ensure the input runnable starts before this one
final_input: Optional[Input] = next(input_for_tracing, None)
final_input_supported = True
final_output: Optional[Output] = None
final_output_supported = True
config = ensure_config(config)
callback_manager = get_callback_manager_for_config(config)
run_manager = callback_manager.on_chain_start(
dumpd(self),
{"input": ""},
run_type=run_type,
name=config.get("run_name") or self.get_name(),
)
try:
child_config = patch_config(config, callbacks=run_manager.get_child())
if accepts_config(transformer):
kwargs["config"] = child_config
if accepts_run_manager(transformer):
kwargs["run_manager"] = run_manager
context = copy_context()
context.run(var_child_runnable_config.set, child_config)
iterator = context.run(transformer, input_for_transform, **kwargs) # type: ignore[arg-type]
try:
while True:
chunk: Output = context.run(next, iterator) # type: ignore
yield chunk
if final_output_supported:
if final_output is None:
final_output = chunk
else:
try:
final_output = final_output + chunk # type: ignore
except TypeError:
final_output = None
final_output_supported = False
except StopIteration:
pass
for ichunk in input_for_tracing:
if final_input_supported:
if final_input is None:
final_input = ichunk
else:
try:
final_input = final_input + ichunk # type: ignore
except TypeError:
final_input = None
final_input_supported = False
except BaseException as e:
run_manager.on_chain_error(e, inputs=final_input)
raise
else:
run_manager.on_chain_end(final_output, inputs=final_input)
async def _atransform_stream_with_config(
self,
input: AsyncIterator[Input],
transformer: Union[
Callable[[AsyncIterator[Input]], AsyncIterator[Output]],
Callable[
[AsyncIterator[Input], AsyncCallbackManagerForChainRun],
AsyncIterator[Output],
],
Callable[
[
AsyncIterator[Input],
AsyncCallbackManagerForChainRun,
RunnableConfig,
],
AsyncIterator[Output],
],
],
config: Optional[RunnableConfig],
run_type: Optional[str] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[Output]:
"""Helper method to transform an Async Iterator of Input values into an Async
Iterator of Output values, with callbacks.
Use this to implement `astream()` or `atransform()` in Runnable subclasses."""
# tee the input so we can iterate over it twice
input_for_tracing, input_for_transform = atee(input, 2)
# Start the input iterator to ensure the input runnable starts before this one
final_input: Optional[Input] = await py_anext(input_for_tracing, None)
final_input_supported = True
final_output: Optional[Output] = None
final_output_supported = True
config = ensure_config(config)
callback_manager = get_async_callback_manager_for_config(config)
run_manager = await callback_manager.on_chain_start(
dumpd(self),
{"input": ""},
run_type=run_type,
name=config.get("run_name") or self.get_name(),
)
try:
child_config = patch_config(config, callbacks=run_manager.get_child())
if accepts_config(transformer):
kwargs["config"] = child_config
if accepts_run_manager(transformer):
kwargs["run_manager"] = run_manager
context = copy_context()
context.run(var_child_runnable_config.set, child_config)
iterator = context.run(transformer, input_for_transform, **kwargs) # type: ignore[arg-type]
try:
while True:
if accepts_context(asyncio.create_task):
chunk: Output = await asyncio.create_task( # type: ignore[call-arg]
py_anext(iterator), # type: ignore[arg-type]
context=context,
)
else:
chunk = cast(Output, await py_anext(iterator))
yield chunk
if final_output_supported:
if final_output is None:
final_output = chunk
else:
try:
final_output = final_output + chunk # type: ignore
except TypeError:
final_output = None
final_output_supported = False
except StopAsyncIteration:
pass
async for ichunk in input_for_tracing:
if final_input_supported:
if final_input is None:
final_input = ichunk
else:
try:
final_input = final_input + ichunk # type: ignore[operator]
except TypeError:
final_input = None
final_input_supported = False
except BaseException as e:
await run_manager.on_chain_error(e, inputs=final_input)
raise
else:
await run_manager.on_chain_end(final_output, inputs=final_input)
[docs]class RunnableSerializable(Serializable, Runnable[Input, Output]):
"""A Runnable that can be serialized to JSON."""
name: Optional[str] = None
"""The name of the runnable. Used for debugging and tracing."""
[docs] def configurable_fields(
self, **kwargs: AnyConfigurableField
) -> RunnableSerializable[Input, Output]:
from langchain_core.runnables.configurable import RunnableConfigurableFields
for key in kwargs:
if key not in self.__fields__:
raise ValueError(
f"Configuration key {key} not found in {self}: "
"available keys are {self.__fields__.keys()}"
)
return RunnableConfigurableFields(default=self, fields=kwargs)
[docs] def configurable_alternatives(
self,
which: ConfigurableField,
*,
default_key: str = "default",
prefix_keys: bool = False,
**kwargs: Union[Runnable[Input, Output], Callable[[], Runnable[Input, Output]]],
) -> RunnableSerializable[Input, Output]:
from langchain_core.runnables.configurable import (
RunnableConfigurableAlternatives,
)
return RunnableConfigurableAlternatives(
which=which,
default=self,
alternatives=kwargs,
default_key=default_key,
prefix_keys=prefix_keys,
)
def _seq_input_schema(
steps: List[Runnable[Any, Any]], config: Optional[RunnableConfig]
) -> Type[BaseModel]:
from langchain_core.runnables.passthrough import RunnableAssign, RunnablePick
first = steps[0]
if len(steps) == 1:
return first.get_input_schema(config)
elif isinstance(first, RunnableAssign):
next_input_schema = _seq_input_schema(steps[1:], config)
if not next_input_schema.__custom_root_type__:
# it's a dict as expected
return create_model( # type: ignore[call-overload]
"RunnableSequenceInput",
**{
k: (v.annotation, v.default)
for k, v in next_input_schema.__fields__.items()
if k not in first.mapper.steps
},
__config__=_SchemaConfig,
)
elif isinstance(first, RunnablePick):
return _seq_input_schema(steps[1:], config)
return first.get_input_schema(config)
def _seq_output_schema(
steps: List[Runnable[Any, Any]], config: Optional[RunnableConfig]
) -> Type[BaseModel]:
from langchain_core.runnables.passthrough import RunnableAssign, RunnablePick
last = steps[-1]
if len(steps) == 1:
return last.get_input_schema(config)
elif isinstance(last, RunnableAssign):
mapper_output_schema = last.mapper.get_output_schema(config)
prev_output_schema = _seq_output_schema(steps[:-1], config)
if not prev_output_schema.__custom_root_type__:
# it's a dict as expected
return create_model( # type: ignore[call-overload]
"RunnableSequenceOutput",
**{
**{
k: (v.annotation, v.default)
for k, v in prev_output_schema.__fields__.items()
},
**{
k: (v.annotation, v.default)
for k, v in mapper_output_schema.__fields__.items()
},
},
__config__=_SchemaConfig,
)
elif isinstance(last, RunnablePick):
prev_output_schema = _seq_output_schema(steps[:-1], config)
if not prev_output_schema.__custom_root_type__:
# it's a dict as expected
if isinstance(last.keys, list):
return create_model( # type: ignore[call-overload]
"RunnableSequenceOutput",
**{
k: (v.annotation, v.default)
for k, v in prev_output_schema.__fields__.items()
if k in last.keys
},
__config__=_SchemaConfig,
)
else:
field = prev_output_schema.__fields__[last.keys]
return create_model( # type: ignore[call-overload]
"RunnableSequenceOutput",
__root__=(field.annotation, field.default),
__config__=_SchemaConfig,
)
return last.get_output_schema(config)
[docs]class RunnableSequence(RunnableSerializable[Input, Output]):
"""A sequence of runnables, where the output of each is the input of the next.
RunnableSequence is the most important composition operator in LangChain as it is
used in virtually every chain.
A RunnableSequence can be instantiated directly or more commonly by using the `|`
operator where either the left or right operands (or both) must be a Runnable.
Any RunnableSequence automatically supports sync, async, batch.
The default implementations of `batch` and `abatch` utilize threadpools and
asyncio gather and will be faster than naive invocation of invoke or ainvoke
for IO bound runnables.
Batching is implemented by invoking the batch method on each component of the
RunnableSequence in order.
A RunnableSequence preserves the streaming properties of its components, so if all
components of the sequence implement a `transform` method -- which
is the method that implements the logic to map a streaming input to a streaming
output -- then the sequence will be able to stream input to output!
If any component of the sequence does not implement transform then the
streaming will only begin after this component is run. If there are
multiple blocking components, streaming begins after the last one.
Please note: RunnableLambdas do not support `transform` by default! So if
you need to use a RunnableLambdas be careful about where you place them in a
RunnableSequence (if you need to use the .stream()/.astream() methods).
If you need arbitrary logic and need streaming, you can subclass
Runnable, and implement `transform` for whatever logic you need.
Here is a simple example that uses simple functions to illustrate the use of
RunnableSequence:
.. code-block:: python
from langchain_core.runnables import RunnableLambda
def add_one(x: int) -> int:
return x + 1
def mul_two(x: int) -> int:
return x * 2
runnable_1 = RunnableLambda(add_one)
runnable_2 = RunnableLambda(mul_two)
sequence = runnable_1 | runnable_2
# Or equivalently:
# sequence = RunnableSequence(first=runnable_1, last=runnable_2)
sequence.invoke(1)
await runnable.ainvoke(1)
sequence.batch([1, 2, 3])
await sequence.abatch([1, 2, 3])
Here's an example that uses streams JSON output generated by an LLM:
.. code-block:: python
from langchain_core.output_parsers.json import SimpleJsonOutputParser
from langchain.chat_models.openai import ChatOpenAI
prompt = PromptTemplate.from_template(
'In JSON format, give me a list of {topic} and their '
'corresponding names in French, Spanish and in a '
'Cat Language.'
)
model = ChatOpenAI()
chain = prompt | model | SimpleJsonOutputParser()
async for chunk in chain.astream({'topic': 'colors'}):
print('-')
print(chunk, sep='', flush=True)
"""
# The steps are broken into first, middle and last, solely for type checking
# purposes. It allows specifying the `Input` on the first type, the `Output` of
# the last type.
first: Runnable[Input, Any]
"""The first runnable in the sequence."""
middle: List[Runnable[Any, Any]] = Field(default_factory=list)
"""The middle runnables in the sequence."""
last: Runnable[Any, Output]
"""The last runnable in the sequence."""
def __init__(
self,
*steps: RunnableLike,
name: Optional[str] = None,
first: Optional[Runnable[Any, Any]] = None,
middle: Optional[List[Runnable[Any, Any]]] = None,
last: Optional[Runnable[Any, Any]] = None,
) -> None:
"""Create a new RunnableSequence.
Args:
steps: The steps to include in the sequence.
"""
steps_flat: List[Runnable] = []
if not steps:
if first is not None and last is not None:
steps_flat = [first] + (middle or []) + [last]
for step in steps:
if isinstance(step, RunnableSequence):
steps_flat.extend(step.steps)
else:
steps_flat.append(coerce_to_runnable(step))
if len(steps_flat) < 2:
raise ValueError(
f"RunnableSequence must have at least 2 steps, got {len(steps_flat)}"
)
super().__init__(
first=steps_flat[0],
middle=list(steps_flat[1:-1]),
last=steps_flat[-1],
name=name,
)
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
@property
def steps(self) -> List[Runnable[Any, Any]]:
"""All the runnables that make up the sequence in order."""
return [self.first] + self.middle + [self.last]
[docs] @classmethod
def is_lc_serializable(cls) -> bool:
return True
class Config:
arbitrary_types_allowed = True
@property
def InputType(self) -> Type[Input]:
return self.first.InputType
@property
def OutputType(self) -> Type[Output]:
return self.last.OutputType
[docs] def get_output_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
return _seq_output_schema(self.steps, config)
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
from langchain_core.beta.runnables.context import (
CONTEXT_CONFIG_PREFIX,
_key_from_id,
)
# get all specs
all_specs = [
(spec, idx)
for idx, step in enumerate(self.steps)
for spec in step.config_specs
]
# calculate context dependencies
specs_by_pos = groupby(
[tup for tup in all_specs if tup[0].id.startswith(CONTEXT_CONFIG_PREFIX)],
lambda x: x[1],
)
next_deps: Set[str] = set()
deps_by_pos: Dict[int, Set[str]] = {}
for pos, specs in specs_by_pos:
deps_by_pos[pos] = next_deps
next_deps = next_deps | {spec[0].id for spec in specs}
# assign context dependencies
for pos, (spec, idx) in enumerate(all_specs):
if spec.id.startswith(CONTEXT_CONFIG_PREFIX):
all_specs[pos] = (
ConfigurableFieldSpec(
id=spec.id,
annotation=spec.annotation,
name=spec.name,
default=spec.default,
description=spec.description,
is_shared=spec.is_shared,
dependencies=[
d
for d in deps_by_pos[idx]
if _key_from_id(d) != _key_from_id(spec.id)
]
+ (spec.dependencies or []),
),
idx,
)
return get_unique_config_specs(spec for spec, _ in all_specs)
[docs] def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
from langchain_core.runnables.graph import Graph
graph = Graph()
for step in self.steps:
current_last_node = graph.last_node()
step_graph = step.get_graph(config)
if step is not self.first:
step_graph.trim_first_node()
if step is not self.last:
step_graph.trim_last_node()
graph.extend(step_graph)
step_first_node = step_graph.first_node()
if not step_first_node:
raise ValueError(f"Runnable {step} has no first node")
if current_last_node:
graph.add_edge(current_last_node, step_first_node)
return graph
def __repr__(self) -> str:
return "\n| ".join(
repr(s) if i == 0 else indent_lines_after_first(repr(s), "| ")
for i, s in enumerate(self.steps)
)
def __or__(
self,
other: Union[
Runnable[Any, Other],
Callable[[Any], Other],
Callable[[Iterator[Any]], Iterator[Other]],
Mapping[str, Union[Runnable[Any, Other], Callable[[Any], Other], Any]],
],
) -> RunnableSerializable[Input, Other]:
if isinstance(other, RunnableSequence):
return RunnableSequence(
self.first,
*self.middle,
self.last,
other.first,
*other.middle,
other.last,
name=self.name or other.name,
)
else:
return RunnableSequence(
self.first,
*self.middle,
self.last,
coerce_to_runnable(other),
name=self.name,
)
def __ror__(
self,
other: Union[
Runnable[Other, Any],
Callable[[Other], Any],
Callable[[Iterator[Other]], Iterator[Any]],
Mapping[str, Union[Runnable[Other, Any], Callable[[Other], Any], Any]],
],
) -> RunnableSerializable[Other, Output]:
if isinstance(other, RunnableSequence):
return RunnableSequence(
other.first,
*other.middle,
other.last,
self.first,
*self.middle,
self.last,
name=other.name or self.name,
)
else:
return RunnableSequence(
coerce_to_runnable(other),
self.first,
*self.middle,
self.last,
name=self.name,
)
[docs] def invoke(self, input: Input, config: Optional[RunnableConfig] = None) -> Output:
from langchain_core.beta.runnables.context import config_with_context
# setup callbacks and context
config = config_with_context(ensure_config(config), self.steps)
callback_manager = get_callback_manager_for_config(config)
# start the root run
run_manager = callback_manager.on_chain_start(
dumpd(self), input, name=config.get("run_name") or self.get_name()
)
# invoke all steps in sequence
try:
for i, step in enumerate(self.steps):
input = step.invoke(
input,
# mark each step as a child run
patch_config(
config, callbacks=run_manager.get_child(f"seq:step:{i+1}")
),
)
# finish the root run
except BaseException as e:
run_manager.on_chain_error(e)
raise
else:
run_manager.on_chain_end(input)
return cast(Output, input)
[docs] async def ainvoke(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Output:
from langchain_core.beta.runnables.context import aconfig_with_context
# setup callbacks and context
config = aconfig_with_context(ensure_config(config), self.steps)
callback_manager = get_async_callback_manager_for_config(config)
# start the root run
run_manager = await callback_manager.on_chain_start(
dumpd(self), input, name=config.get("run_name") or self.get_name()
)
# invoke all steps in sequence
try:
for i, step in enumerate(self.steps):
input = await step.ainvoke(
input,
# mark each step as a child run
patch_config(
config, callbacks=run_manager.get_child(f"seq:step:{i+1}")
),
)
# finish the root run
except BaseException as e:
await run_manager.on_chain_error(e)
raise
else:
await run_manager.on_chain_end(input)
return cast(Output, input)
[docs] def batch(
self,
inputs: List[Input],
config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
**kwargs: Optional[Any],
) -> List[Output]:
from langchain_core.beta.runnables.context import config_with_context
from langchain_core.callbacks.manager import CallbackManager
if not inputs:
return []
# setup callbacks and context
configs = [
config_with_context(c, self.steps)
for c in get_config_list(config, len(inputs))
]
callback_managers = [
CallbackManager.configure(
inheritable_callbacks=config.get("callbacks"),
local_callbacks=None,
verbose=False,
inheritable_tags=config.get("tags"),
local_tags=None,
inheritable_metadata=config.get("metadata"),
local_metadata=None,
)
for config in configs
]
# start the root runs, one per input
run_managers = [
cm.on_chain_start(
dumpd(self),
input,
name=config.get("run_name") or self.get_name(),
)
for cm, input, config in zip(callback_managers, inputs, configs)
]
# invoke
try:
if return_exceptions:
# Track which inputs (by index) failed so far
# If an input has failed it will be present in this map,
# and the value will be the exception that was raised.
failed_inputs_map: Dict[int, Exception] = {}
for stepidx, step in enumerate(self.steps):
# Assemble the original indexes of the remaining inputs
# (i.e. the ones that haven't failed yet)
remaining_idxs = [
i for i in range(len(configs)) if i not in failed_inputs_map
]
# Invoke the step on the remaining inputs
inputs = step.batch(
[
inp
for i, inp in zip(remaining_idxs, inputs)
if i not in failed_inputs_map
],
[
# each step a child run of the corresponding root run
patch_config(
config, callbacks=rm.get_child(f"seq:step:{stepidx+1}")
)
for i, (rm, config) in enumerate(zip(run_managers, configs))
if i not in failed_inputs_map
],
return_exceptions=return_exceptions,
**kwargs,
)
# If an input failed, add it to the map
for i, inp in zip(remaining_idxs, inputs):
if isinstance(inp, Exception):
failed_inputs_map[i] = inp
inputs = [inp for inp in inputs if not isinstance(inp, Exception)]
# If all inputs have failed, stop processing
if len(failed_inputs_map) == len(configs):
break
# Reassemble the outputs, inserting Exceptions for failed inputs
inputs_copy = inputs.copy()
inputs = []
for i in range(len(configs)):
if i in failed_inputs_map:
inputs.append(cast(Input, failed_inputs_map[i]))
else:
inputs.append(inputs_copy.pop(0))
else:
for i, step in enumerate(self.steps):
inputs = step.batch(
inputs,
[
# each step a child run of the corresponding root run
patch_config(
config, callbacks=rm.get_child(f"seq:step:{i+1}")
)
for rm, config in zip(run_managers, configs)
],
)
# finish the root runs
except BaseException as e:
for rm in run_managers:
rm.on_chain_error(e)
if return_exceptions:
return cast(List[Output], [e for _ in inputs])
else:
raise
else:
first_exception: Optional[Exception] = None
for run_manager, out in zip(run_managers, inputs):
if isinstance(out, Exception):
first_exception = first_exception or out
run_manager.on_chain_error(out)
else:
run_manager.on_chain_end(dumpd(out))
if return_exceptions or first_exception is None:
return cast(List[Output], inputs)
else:
raise first_exception
[docs] async def abatch(
self,
inputs: List[Input],
config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
**kwargs: Optional[Any],
) -> List[Output]:
from langchain_core.beta.runnables.context import aconfig_with_context
from langchain_core.callbacks.manager import AsyncCallbackManager
if not inputs:
return []
# setup callbacks and context
configs = [
aconfig_with_context(c, self.steps)
for c in get_config_list(config, len(inputs))
]
callback_managers = [
AsyncCallbackManager.configure(
inheritable_callbacks=config.get("callbacks"),
local_callbacks=None,
verbose=False,
inheritable_tags=config.get("tags"),
local_tags=None,
inheritable_metadata=config.get("metadata"),
local_metadata=None,
)
for config in configs
]
# start the root runs, one per input
run_managers: List[AsyncCallbackManagerForChainRun] = await asyncio.gather(
*(
cm.on_chain_start(
dumpd(self),
input,
name=config.get("run_name") or self.get_name(),
)
for cm, input, config in zip(callback_managers, inputs, configs)
)
)
# invoke .batch() on each step
# this uses batching optimizations in Runnable subclasses, like LLM
try:
if return_exceptions:
# Track which inputs (by index) failed so far
# If an input has failed it will be present in this map,
# and the value will be the exception that was raised.
failed_inputs_map: Dict[int, Exception] = {}
for stepidx, step in enumerate(self.steps):
# Assemble the original indexes of the remaining inputs
# (i.e. the ones that haven't failed yet)
remaining_idxs = [
i for i in range(len(configs)) if i not in failed_inputs_map
]
# Invoke the step on the remaining inputs
inputs = await step.abatch(
[
inp
for i, inp in zip(remaining_idxs, inputs)
if i not in failed_inputs_map
],
[
# each step a child run of the corresponding root run
patch_config(
config, callbacks=rm.get_child(f"seq:step:{stepidx+1}")
)
for i, (rm, config) in enumerate(zip(run_managers, configs))
if i not in failed_inputs_map
],
return_exceptions=return_exceptions,
**kwargs,
)
# If an input failed, add it to the map
for i, inp in zip(remaining_idxs, inputs):
if isinstance(inp, Exception):
failed_inputs_map[i] = inp
inputs = [inp for inp in inputs if not isinstance(inp, Exception)]
# If all inputs have failed, stop processing
if len(failed_inputs_map) == len(configs):
break
# Reassemble the outputs, inserting Exceptions for failed inputs
inputs_copy = inputs.copy()
inputs = []
for i in range(len(configs)):
if i in failed_inputs_map:
inputs.append(cast(Input, failed_inputs_map[i]))
else:
inputs.append(inputs_copy.pop(0))
else:
for i, step in enumerate(self.steps):
inputs = await step.abatch(
inputs,
[
# each step a child run of the corresponding root run
patch_config(
config, callbacks=rm.get_child(f"seq:step:{i+1}")
)
for rm, config in zip(run_managers, configs)
],
)
# finish the root runs
except BaseException as e:
await asyncio.gather(*(rm.on_chain_error(e) for rm in run_managers))
if return_exceptions:
return cast(List[Output], [e for _ in inputs])
else:
raise
else:
first_exception: Optional[Exception] = None
coros: List[Awaitable[None]] = []
for run_manager, out in zip(run_managers, inputs):
if isinstance(out, Exception):
first_exception = first_exception or out
coros.append(run_manager.on_chain_error(out))
else:
coros.append(run_manager.on_chain_end(dumpd(out)))
await asyncio.gather(*coros)
if return_exceptions or first_exception is None:
return cast(List[Output], inputs)
else:
raise first_exception
def _transform(
self,
input: Iterator[Input],
run_manager: CallbackManagerForChainRun,
config: RunnableConfig,
) -> Iterator[Output]:
from langchain_core.beta.runnables.context import config_with_context
steps = [self.first] + self.middle + [self.last]
config = config_with_context(config, self.steps)
# transform the input stream of each step with the next
# steps that don't natively support transforming an input stream will
# buffer input in memory until all available, and then start emitting output
final_pipeline = cast(Iterator[Output], input)
for step in steps:
final_pipeline = step.transform(
final_pipeline,
patch_config(
config,
callbacks=run_manager.get_child(f"seq:step:{steps.index(step)+1}"),
),
)
for output in final_pipeline:
yield output
async def _atransform(
self,
input: AsyncIterator[Input],
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
) -> AsyncIterator[Output]:
from langchain_core.beta.runnables.context import aconfig_with_context
steps = [self.first] + self.middle + [self.last]
config = aconfig_with_context(config, self.steps)
# stream the last steps
# transform the input stream of each step with the next
# steps that don't natively support transforming an input stream will
# buffer input in memory until all available, and then start emitting output
final_pipeline = cast(AsyncIterator[Output], input)
for step in steps:
final_pipeline = step.atransform(
final_pipeline,
patch_config(
config,
callbacks=run_manager.get_child(f"seq:step:{steps.index(step)+1}"),
),
)
async for output in final_pipeline:
yield output
[docs] def stream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Iterator[Output]:
yield from self.transform(iter([input]), config, **kwargs)
[docs] async def astream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[Output]:
async def input_aiter() -> AsyncIterator[Input]:
yield input
async for chunk in self.atransform(input_aiter(), config, **kwargs):
yield chunk
[docs]class RunnableParallel(RunnableSerializable[Input, Dict[str, Any]]):
"""
A runnable that runs a mapping of runnables in parallel,
and returns a mapping of their outputs.
"""
steps: Mapping[str, Runnable[Input, Any]]
def __init__(
self,
__steps: Optional[
Mapping[
str,
Union[
Runnable[Input, Any],
Callable[[Input], Any],
Mapping[str, Union[Runnable[Input, Any], Callable[[Input], Any]]],
],
]
] = None,
**kwargs: Union[
Runnable[Input, Any],
Callable[[Input], Any],
Mapping[str, Union[Runnable[Input, Any], Callable[[Input], Any]]],
],
) -> None:
merged = {**__steps} if __steps is not None else {}
merged.update(kwargs)
super().__init__(
steps={key: coerce_to_runnable(r) for key, r in merged.items()}
)
[docs] @classmethod
def is_lc_serializable(cls) -> bool:
return True
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
class Config:
arbitrary_types_allowed = True
[docs] def get_name(
self, suffix: Optional[str] = None, *, name: Optional[str] = None
) -> str:
name = name or self.name or f"RunnableParallel<{','.join(self.steps.keys())}>"
return super().get_name(suffix, name=name)
@property
def InputType(self) -> Any:
for step in self.steps.values():
if step.InputType:
return step.InputType
return Any
[docs] def get_output_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
# This is correct, but pydantic typings/mypy don't think so.
return create_model( # type: ignore[call-overload]
self.get_name("Output"),
**{k: (v.OutputType, None) for k, v in self.steps.items()},
__config__=_SchemaConfig,
)
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
return get_unique_config_specs(
spec for step in self.steps.values() for spec in step.config_specs
)
[docs] def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
from langchain_core.runnables.graph import Graph
graph = Graph()
input_node = graph.add_node(self.get_input_schema(config))
output_node = graph.add_node(self.get_output_schema(config))
for step in self.steps.values():
step_graph = step.get_graph()
step_graph.trim_first_node()
step_graph.trim_last_node()
if not step_graph:
graph.add_edge(input_node, output_node)
else:
graph.extend(step_graph)
step_first_node = step_graph.first_node()
if not step_first_node:
raise ValueError(f"Runnable {step} has no first node")
step_last_node = step_graph.last_node()
if not step_last_node:
raise ValueError(f"Runnable {step} has no last node")
graph.add_edge(input_node, step_first_node)
graph.add_edge(step_last_node, output_node)
return graph
def __repr__(self) -> str:
map_for_repr = ",\n ".join(
f"{k}: {indent_lines_after_first(repr(v), ' ' + k + ': ')}"
for k, v in self.steps.items()
)
return "{\n " + map_for_repr + "\n}"
[docs] def invoke(
self, input: Input, config: Optional[RunnableConfig] = None
) -> Dict[str, Any]:
from langchain_core.callbacks.manager import CallbackManager
# setup callbacks
config = ensure_config(config)
callback_manager = CallbackManager.configure(
inheritable_callbacks=config.get("callbacks"),
local_callbacks=None,
verbose=False,
inheritable_tags=config.get("tags"),
local_tags=None,
inheritable_metadata=config.get("metadata"),
local_metadata=None,
)
# start the root run
run_manager = callback_manager.on_chain_start(
dumpd(self), input, name=config.get("run_name") or self.get_name()
)
# gather results from all steps
try:
# copy to avoid issues from the caller mutating the steps during invoke()
steps = dict(self.steps)
with get_executor_for_config(config) as executor:
futures = [
executor.submit(
step.invoke,
input,
# mark each step as a child run
patch_config(
config,
callbacks=run_manager.get_child(f"map:key:{key}"),
),
)
for key, step in steps.items()
]
output = {key: future.result() for key, future in zip(steps, futures)}
# finish the root run
except BaseException as e:
run_manager.on_chain_error(e)
raise
else:
run_manager.on_chain_end(output)
return output
[docs] async def ainvoke(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Dict[str, Any]:
# setup callbacks
config = ensure_config(config)
callback_manager = get_async_callback_manager_for_config(config)
# start the root run
run_manager = await callback_manager.on_chain_start(
dumpd(self), input, name=config.get("run_name") or self.get_name()
)
# gather results from all steps
try:
# copy to avoid issues from the caller mutating the steps during invoke()
steps = dict(self.steps)
results = await asyncio.gather(
*(
step.ainvoke(
input,
# mark each step as a child run
patch_config(
config, callbacks=run_manager.get_child(f"map:key:{key}")
),
)
for key, step in steps.items()
)
)
output = {key: value for key, value in zip(steps, results)}
# finish the root run
except BaseException as e:
await run_manager.on_chain_error(e)
raise
else:
await run_manager.on_chain_end(output)
return output
def _transform(
self,
input: Iterator[Input],
run_manager: CallbackManagerForChainRun,
config: RunnableConfig,
) -> Iterator[AddableDict]:
# Shallow copy steps to ignore mutations while in progress
steps = dict(self.steps)
# Each step gets a copy of the input iterator,
# which is consumed in parallel in a separate thread.
input_copies = list(safetee(input, len(steps), lock=threading.Lock()))
with get_executor_for_config(config) as executor:
# Create the transform() generator for each step
named_generators = [
(
name,
step.transform(
input_copies.pop(),
patch_config(
config, callbacks=run_manager.get_child(f"map:key:{name}")
),
),
)
for name, step in steps.items()
]
# Start the first iteration of each generator
futures = {
executor.submit(next, generator): (step_name, generator)
for step_name, generator in named_generators
}
# Yield chunks from each as they become available,
# and start the next iteration of that generator that yielded it.
# When all generators are exhausted, stop.
while futures:
completed_futures, _ = wait(futures, return_when=FIRST_COMPLETED)
for future in completed_futures:
(step_name, generator) = futures.pop(future)
try:
chunk = AddableDict({step_name: future.result()})
yield chunk
futures[executor.submit(next, generator)] = (
step_name,
generator,
)
except StopIteration:
pass
[docs] def stream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Iterator[Dict[str, Any]]:
yield from self.transform(iter([input]), config)
async def _atransform(
self,
input: AsyncIterator[Input],
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
) -> AsyncIterator[AddableDict]:
# Shallow copy steps to ignore mutations while in progress
steps = dict(self.steps)
# Each step gets a copy of the input iterator,
# which is consumed in parallel in a separate thread.
input_copies = list(atee(input, len(steps), lock=asyncio.Lock()))
# Create the transform() generator for each step
named_generators = [
(
name,
step.atransform(
input_copies.pop(),
patch_config(
config, callbacks=run_manager.get_child(f"map:key:{name}")
),
),
)
for name, step in steps.items()
]
# Wrap in a coroutine to satisfy linter
async def get_next_chunk(generator: AsyncIterator) -> Optional[Output]:
return await py_anext(generator)
# Start the first iteration of each generator
tasks = {
asyncio.create_task(get_next_chunk(generator)): (step_name, generator)
for step_name, generator in named_generators
}
# Yield chunks from each as they become available,
# and start the next iteration of the generator that yielded it.
# When all generators are exhausted, stop.
while tasks:
completed_tasks, _ = await asyncio.wait(
tasks, return_when=asyncio.FIRST_COMPLETED
)
for task in completed_tasks:
(step_name, generator) = tasks.pop(task)
try:
chunk = AddableDict({step_name: task.result()})
yield chunk
new_task = asyncio.create_task(get_next_chunk(generator))
tasks[new_task] = (step_name, generator)
except StopAsyncIteration:
pass
[docs] async def astream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[Dict[str, Any]]:
async def input_aiter() -> AsyncIterator[Input]:
yield input
async for chunk in self.atransform(input_aiter(), config):
yield chunk
# We support both names
RunnableMap = RunnableParallel
[docs]class RunnableGenerator(Runnable[Input, Output]):
"""
A runnable that runs a generator function.
"""
[docs] def __init__(
self,
transform: Union[
Callable[[Iterator[Input]], Iterator[Output]],
Callable[[AsyncIterator[Input]], AsyncIterator[Output]],
],
atransform: Optional[
Callable[[AsyncIterator[Input]], AsyncIterator[Output]]
] = None,
) -> None:
if atransform is not None:
self._atransform = atransform
func_for_name: Callable = atransform
if inspect.isasyncgenfunction(transform):
self._atransform = transform
func_for_name = transform
elif inspect.isgeneratorfunction(transform):
self._transform = transform
func_for_name = transform
else:
raise TypeError(
"Expected a generator function type for `transform`."
f"Instead got an unsupported type: {type(transform)}"
)
try:
self.name = func_for_name.__name__
except AttributeError:
pass
@property
def InputType(self) -> Any:
func = getattr(self, "_transform", None) or getattr(self, "_atransform")
try:
params = inspect.signature(func).parameters
first_param = next(iter(params.values()), None)
if first_param and first_param.annotation != inspect.Parameter.empty:
return getattr(first_param.annotation, "__args__", (Any,))[0]
else:
return Any
except ValueError:
return Any
@property
def OutputType(self) -> Any:
func = getattr(self, "_transform", None) or getattr(self, "_atransform")
try:
sig = inspect.signature(func)
return (
getattr(sig.return_annotation, "__args__", (Any,))[0]
if sig.return_annotation != inspect.Signature.empty
else Any
)
except ValueError:
return Any
def __eq__(self, other: Any) -> bool:
if isinstance(other, RunnableGenerator):
if hasattr(self, "_transform") and hasattr(other, "_transform"):
return self._transform == other._transform
elif hasattr(self, "_atransform") and hasattr(other, "_atransform"):
return self._atransform == other._atransform
else:
return False
else:
return False
def __repr__(self) -> str:
if hasattr(self, "_transform"):
return f"RunnableGenerator({self._transform.__name__})"
elif hasattr(self, "_atransform"):
return f"RunnableGenerator({self._atransform.__name__})"
else:
return "RunnableGenerator(...)"
[docs] def stream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Iterator[Output]:
return self.transform(iter([input]), config, **kwargs)
[docs] def invoke(
self, input: Input, config: Optional[RunnableConfig] = None, **kwargs: Any
) -> Output:
final = None
for output in self.stream(input, config, **kwargs):
if final is None:
final = output
else:
final = final + output
return cast(Output, final)
[docs] def astream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> AsyncIterator[Output]:
async def input_aiter() -> AsyncIterator[Input]:
yield input
return self.atransform(input_aiter(), config, **kwargs)
[docs] async def ainvoke(
self, input: Input, config: Optional[RunnableConfig] = None, **kwargs: Any
) -> Output:
final = None
async for output in self.astream(input, config, **kwargs):
if final is None:
final = output
else:
final = final + output
return cast(Output, final)
[docs]class RunnableLambda(Runnable[Input, Output]):
"""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:
.. code-block:: python
# 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
"""
[docs] def __init__(
self,
func: Union[
Union[
Callable[[Input], Output],
Callable[[Input], Iterator[Output]],
Callable[[Input, RunnableConfig], Output],
Callable[[Input, CallbackManagerForChainRun], Output],
Callable[[Input, CallbackManagerForChainRun, RunnableConfig], Output],
],
Union[
Callable[[Input], Awaitable[Output]],
Callable[[Input], AsyncIterator[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], AsyncIterator[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.
Args:
func: Either sync or async callable
afunc: An async callable that takes an input and returns an output.
"""
if afunc is not None:
self.afunc = afunc
func_for_name: Callable = afunc
if inspect.iscoroutinefunction(func) or inspect.isasyncgenfunction(func):
if afunc is not None:
raise TypeError(
"Func was provided as a coroutine function, but afunc was "
"also provided. If providing both, func should be a regular "
"function to avoid ambiguity."
)
self.afunc = func
func_for_name = func
elif callable(func):
self.func = cast(Callable[[Input], Output], func)
func_for_name = func
else:
raise TypeError(
"Expected a callable type for `func`."
f"Instead got an unsupported type: {type(func)}"
)
try:
if func_for_name.__name__ != "<lambda>":
self.name = func_for_name.__name__
except AttributeError:
pass
@property
def InputType(self) -> Any:
"""The type of the input to this runnable."""
func = getattr(self, "func", None) or getattr(self, "afunc")
try:
params = inspect.signature(func).parameters
first_param = next(iter(params.values()), None)
if first_param and first_param.annotation != inspect.Parameter.empty:
return first_param.annotation
else:
return Any
except ValueError:
return Any
@property
def OutputType(self) -> Any:
"""The type of the output of this runnable as a type annotation."""
func = getattr(self, "func", None) or getattr(self, "afunc")
try:
sig = inspect.signature(func)
if sig.return_annotation != inspect.Signature.empty:
# unwrap iterator types
if getattr(sig.return_annotation, "__origin__", None) in (
collections.abc.Iterator,
collections.abc.AsyncIterator,
):
return getattr(sig.return_annotation, "__args__", (Any,))[0]
return sig.return_annotation
else:
return Any
except ValueError:
return Any
@property
def deps(self) -> List[Runnable]:
"""The dependencies of this runnable."""
if hasattr(self, "func"):
objects = get_function_nonlocals(self.func)
elif hasattr(self, "afunc"):
objects = get_function_nonlocals(self.afunc)
else:
objects = []
return [obj for obj in objects if isinstance(obj, Runnable)]
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
return get_unique_config_specs(
spec for dep in self.deps for spec in dep.config_specs
)
[docs] def get_graph(self, config: RunnableConfig | None = None) -> Graph:
if deps := self.deps:
graph = Graph()
input_node = graph.add_node(self.get_input_schema(config))
output_node = graph.add_node(self.get_output_schema(config))
for dep in deps:
dep_graph = dep.get_graph()
dep_graph.trim_first_node()
dep_graph.trim_last_node()
if not dep_graph:
graph.add_edge(input_node, output_node)
else:
graph.extend(dep_graph)
dep_first_node = dep_graph.first_node()
if not dep_first_node:
raise ValueError(f"Runnable {dep} has no first node")
dep_last_node = dep_graph.last_node()
if not dep_last_node:
raise ValueError(f"Runnable {dep} has no last node")
graph.add_edge(input_node, dep_first_node)
graph.add_edge(dep_last_node, output_node)
else:
graph = super().get_graph(config)
return graph
def __eq__(self, other: Any) -> bool:
if isinstance(other, RunnableLambda):
if hasattr(self, "func") and hasattr(other, "func"):
return self.func == other.func
elif hasattr(self, "afunc") and hasattr(other, "afunc"):
return self.afunc == other.afunc
else:
return False
else:
return False
def __repr__(self) -> str:
"""A string representation of this runnable."""
if hasattr(self, "func") and isinstance(self.func, itemgetter):
return f"RunnableLambda({str(self.func)[len('operator.'):]})"
elif hasattr(self, "func"):
return f"RunnableLambda({get_lambda_source(self.func) or '...'})"
elif hasattr(self, "afunc"):
return f"RunnableLambda(afunc={get_lambda_source(self.afunc) or '...'})"
else:
return "RunnableLambda(...)"
def _invoke(
self,
input: Input,
run_manager: CallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> Output:
if inspect.isgeneratorfunction(self.func):
output: Optional[Output] = None
for chunk in call_func_with_variable_args(
cast(Callable[[Input], Iterator[Output]], self.func),
input,
config,
run_manager,
**kwargs,
):
if output is None:
output = chunk
else:
try:
output = output + chunk # type: ignore[operator]
except TypeError:
output = chunk
else:
output = call_func_with_variable_args(
self.func, input, config, run_manager, **kwargs
)
# If the output is a runnable, invoke it
if isinstance(output, Runnable):
recursion_limit = config["recursion_limit"]
if recursion_limit <= 0:
raise RecursionError(
f"Recursion limit reached when invoking {self} with input {input}."
)
output = output.invoke(
input,
patch_config(
config,
callbacks=run_manager.get_child(),
recursion_limit=recursion_limit - 1,
),
)
return cast(Output, output)
async def _ainvoke(
self,
input: Input,
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> Output:
if hasattr(self, "afunc"):
afunc = self.afunc
else:
if inspect.isgeneratorfunction(self.func):
def func(
input: Input,
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
) -> Output:
output: Optional[Output] = None
for chunk in call_func_with_variable_args(
cast(Callable[[Input], Iterator[Output]], self.func),
input,
config,
run_manager.get_sync(),
**kwargs,
):
if output is None:
output = chunk
else:
try:
output = output + chunk # type: ignore[operator]
except TypeError:
output = chunk
return cast(Output, output)
else:
def func(
input: Input,
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
) -> Output:
return call_func_with_variable_args(
self.func, input, config, run_manager.get_sync(), **kwargs
)
@wraps(func)
async def f(*args, **kwargs): # type: ignore[no-untyped-def]
return await run_in_executor(config, func, *args, **kwargs)
afunc = f
if inspect.isasyncgenfunction(afunc):
output: Optional[Output] = None
async for chunk in cast(
AsyncIterator[Output],
acall_func_with_variable_args(
cast(Callable, afunc),
input,
config,
run_manager,
**kwargs,
),
):
if output is None:
output = chunk
else:
try:
output = output + chunk # type: ignore[operator]
except TypeError:
output = chunk
else:
output = await acall_func_with_variable_args(
cast(Callable, afunc), input, config, run_manager, **kwargs
)
# If the output is a runnable, invoke it
if isinstance(output, Runnable):
recursion_limit = config["recursion_limit"]
if recursion_limit <= 0:
raise RecursionError(
f"Recursion limit reached when invoking {self} with input {input}."
)
output = await output.ainvoke(
input,
patch_config(
config,
callbacks=run_manager.get_child(),
recursion_limit=recursion_limit - 1,
),
)
return cast(Output, output)
def _config(
self, config: Optional[RunnableConfig], callable: Callable[..., Any]
) -> RunnableConfig:
config = ensure_config(config)
if config.get("run_name") is None:
try:
run_name = callable.__name__
except AttributeError:
run_name = None
if run_name is not None:
return patch_config(config, run_name=run_name)
return config
[docs] def invoke(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Output:
"""Invoke this runnable synchronously."""
if hasattr(self, "func"):
return self._call_with_config(
self._invoke,
input,
self._config(config, self.func),
**kwargs,
)
else:
raise TypeError(
"Cannot invoke a coroutine function synchronously."
"Use `ainvoke` instead."
)
[docs] async def ainvoke(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Output:
"""Invoke this runnable asynchronously."""
the_func = self.afunc if hasattr(self, "afunc") else self.func
return await self._acall_with_config(
self._ainvoke,
input,
self._config(config, the_func),
**kwargs,
)
def _transform(
self,
input: Iterator[Input],
run_manager: CallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> Iterator[Output]:
final: Optional[Input] = None
for ichunk in input:
if final is None:
final = ichunk
else:
try:
final = final + ichunk # type: ignore[operator]
except TypeError:
final = ichunk
if inspect.isgeneratorfunction(self.func):
output: Optional[Output] = None
for chunk in call_func_with_variable_args(
self.func, cast(Input, final), config, run_manager, **kwargs
):
yield chunk
if output is None:
output = chunk
else:
try:
output = output + chunk
except TypeError:
output = chunk
else:
output = call_func_with_variable_args(
self.func, cast(Input, final), config, run_manager, **kwargs
)
# If the output is a runnable, use its stream output
if isinstance(output, Runnable):
recursion_limit = config["recursion_limit"]
if recursion_limit <= 0:
raise RecursionError(
f"Recursion limit reached when invoking "
f"{self} with input {final}."
)
for chunk in output.stream(
final,
patch_config(
config,
callbacks=run_manager.get_child(),
recursion_limit=recursion_limit - 1,
),
):
yield chunk
elif not inspect.isgeneratorfunction(self.func):
# Otherwise, just yield it
yield cast(Output, output)
[docs] def stream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Iterator[Output]:
return self.transform(iter([input]), config, **kwargs)
async def _atransform(
self,
input: AsyncIterator[Input],
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> AsyncIterator[Output]:
final: Optional[Input] = None
async for ichunk in input:
if final is None:
final = ichunk
else:
try:
final = final + ichunk # type: ignore[operator]
except TypeError:
final = ichunk
if hasattr(self, "afunc"):
afunc = self.afunc
else:
if inspect.isgeneratorfunction(self.func):
raise TypeError(
"Cannot stream from a generator function asynchronously."
"Use .stream() instead."
)
def func(
input: Input,
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
) -> Output:
return call_func_with_variable_args(
self.func, input, config, run_manager.get_sync(), **kwargs
)
@wraps(func)
async def f(*args, **kwargs): # type: ignore[no-untyped-def]
return await run_in_executor(config, func, *args, **kwargs)
afunc = f
if inspect.isasyncgenfunction(afunc):
output: Optional[Output] = None
async for chunk in cast(
AsyncIterator[Output],
acall_func_with_variable_args(
cast(Callable, afunc),
cast(Input, final),
config,
run_manager,
**kwargs,
),
):
yield chunk
if output is None:
output = chunk
else:
try:
output = output + chunk # type: ignore[operator]
except TypeError:
output = chunk
else:
output = await acall_func_with_variable_args(
cast(Callable, afunc), cast(Input, final), config, run_manager, **kwargs
)
# If the output is a runnable, use its astream output
if isinstance(output, Runnable):
recursion_limit = config["recursion_limit"]
if recursion_limit <= 0:
raise RecursionError(
f"Recursion limit reached when invoking "
f"{self} with input {final}."
)
async for chunk in output.astream(
final,
patch_config(
config,
callbacks=run_manager.get_child(),
recursion_limit=recursion_limit - 1,
),
):
yield chunk
elif not inspect.isasyncgenfunction(afunc):
# Otherwise, just yield it
yield cast(Output, output)
[docs] async def astream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[Output]:
async def input_aiter() -> AsyncIterator[Input]:
yield input
async for chunk in self.atransform(input_aiter(), config, **kwargs):
yield chunk
[docs]class RunnableEachBase(RunnableSerializable[List[Input], List[Output]]):
"""
A runnable that delegates calls to another runnable
with each element of the input sequence.
Use only if creating a new RunnableEach subclass with different __init__ args.
"""
bound: Runnable[Input, Output]
class Config:
arbitrary_types_allowed = True
@property
def InputType(self) -> Any:
return List[self.bound.InputType] # type: ignore[name-defined]
@property
def OutputType(self) -> Type[List[Output]]:
return List[self.bound.OutputType] # type: ignore[name-defined]
[docs] def get_output_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
schema = self.bound.get_output_schema(config)
return create_model(
self.get_name("Output"),
__root__=(
List[schema], # type: ignore
None,
),
__config__=_SchemaConfig,
)
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
return self.bound.config_specs
[docs] def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
return self.bound.get_graph(config)
[docs] @classmethod
def is_lc_serializable(cls) -> bool:
return True
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
def _invoke(
self,
inputs: List[Input],
run_manager: CallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> List[Output]:
return self.bound.batch(
inputs, patch_config(config, callbacks=run_manager.get_child()), **kwargs
)
[docs] def invoke(
self, input: List[Input], config: Optional[RunnableConfig] = None, **kwargs: Any
) -> List[Output]:
return self._call_with_config(self._invoke, input, config, **kwargs)
async def _ainvoke(
self,
inputs: List[Input],
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> List[Output]:
return await self.bound.abatch(
inputs, patch_config(config, callbacks=run_manager.get_child()), **kwargs
)
[docs] async def ainvoke(
self, input: List[Input], config: Optional[RunnableConfig] = None, **kwargs: Any
) -> List[Output]:
return await self._acall_with_config(self._ainvoke, input, config, **kwargs)
[docs]class RunnableEach(RunnableEachBase[Input, Output]):
"""
A runnable that delegates calls to another runnable
with each element of the input sequence.
"""
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
[docs] def get_name(
self, suffix: Optional[str] = None, *, name: Optional[str] = None
) -> str:
name = name or self.name or f"RunnableEach<{self.bound.get_name()}>"
return super().get_name(suffix, name=name)
[docs] def bind(self, **kwargs: Any) -> RunnableEach[Input, Output]:
return RunnableEach(bound=self.bound.bind(**kwargs))
[docs] def with_config(
self, config: Optional[RunnableConfig] = None, **kwargs: Any
) -> RunnableEach[Input, Output]:
return RunnableEach(bound=self.bound.with_config(config, **kwargs))
[docs] def with_listeners(
self,
*,
on_start: Optional[Listener] = None,
on_end: Optional[Listener] = None,
on_error: Optional[Listener] = None,
) -> RunnableEach[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.
"""
return RunnableEach(
bound=self.bound.with_listeners(
on_start=on_start, on_end=on_end, on_error=on_error
)
)
[docs]class RunnableBindingBase(RunnableSerializable[Input, Output]):
"""A runnable that delegates calls to another runnable with a set of kwargs.
Use only if creating a new RunnableBinding subclass with different __init__ args.
See documentation for RunnableBinding for more details.
"""
bound: Runnable[Input, Output]
"""The underlying runnable that this runnable delegates to."""
kwargs: Mapping[str, Any] = Field(default_factory=dict)
"""kwargs to pass to the underlying runnable when running.
For example, when the runnable binding is invoked the underlying
runnable will be invoked with the same input but with these additional
kwargs.
"""
config: RunnableConfig = Field(default_factory=dict)
"""The config to bind to the underlying runnable."""
config_factories: List[Callable[[RunnableConfig], RunnableConfig]] = Field(
default_factory=list
)
"""The config factories to bind to the underlying runnable."""
# Union[Type[Input], BaseModel] + things like List[str]
custom_input_type: Optional[Any] = None
"""Override the input type of the underlying runnable with a custom type.
The type can be a pydantic model, or a type annotation (e.g., `List[str]`).
"""
# Union[Type[Output], BaseModel] + things like List[str]
custom_output_type: Optional[Any] = None
"""Override the output type of the underlying runnable with a custom type.
The type can be a pydantic model, or a type annotation (e.g., `List[str]`).
"""
class Config:
arbitrary_types_allowed = True
def __init__(
self,
*,
bound: Runnable[Input, Output],
kwargs: Optional[Mapping[str, Any]] = None,
config: Optional[RunnableConfig] = None,
config_factories: Optional[
List[Callable[[RunnableConfig], RunnableConfig]]
] = None,
custom_input_type: Optional[Union[Type[Input], BaseModel]] = None,
custom_output_type: Optional[Union[Type[Output], BaseModel]] = None,
**other_kwargs: Any,
) -> None:
"""Create a RunnableBinding from a runnable and kwargs.
Args:
bound: The underlying runnable that this runnable delegates calls to.
kwargs: optional kwargs to pass to the underlying runnable, when running
the underlying runnable (e.g., via `invoke`, `batch`,
`transform`, or `stream` or async variants)
config: config_factories:
config_factories: optional list of config factories to apply to the
custom_input_type: Specify to override the input type of the underlying
runnable with a custom type.
custom_output_type: Specify to override the output type of the underlying
runnable with a custom type.
**other_kwargs: Unpacked into the base class.
"""
config = config or {}
# config_specs contains the list of valid `configurable` keys
if configurable := config.get("configurable", None):
allowed_keys = set(s.id for s in bound.config_specs)
for key in configurable:
if key not in allowed_keys:
raise ValueError(
f"Configurable key '{key}' not found in runnable with"
f" config keys: {allowed_keys}"
)
super().__init__(
bound=bound,
kwargs=kwargs or {},
config=config or {},
config_factories=config_factories or [],
custom_input_type=custom_input_type,
custom_output_type=custom_output_type,
**other_kwargs,
)
[docs] def get_name(
self, suffix: Optional[str] = None, *, name: Optional[str] = None
) -> str:
return self.bound.get_name(suffix, name=name)
@property
def InputType(self) -> Type[Input]:
return (
cast(Type[Input], self.custom_input_type)
if self.custom_input_type is not None
else self.bound.InputType
)
@property
def OutputType(self) -> Type[Output]:
return (
cast(Type[Output], self.custom_output_type)
if self.custom_output_type is not None
else self.bound.OutputType
)
[docs] def get_output_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
if self.custom_output_type is not None:
return super().get_output_schema(config)
return self.bound.get_output_schema(merge_configs(self.config, config))
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
return self.bound.config_specs
[docs] def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
return self.bound.get_graph(config)
[docs] @classmethod
def is_lc_serializable(cls) -> bool:
return True
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
def _merge_configs(self, *configs: Optional[RunnableConfig]) -> RunnableConfig:
config = merge_configs(self.config, *configs)
return merge_configs(config, *(f(config) for f in self.config_factories))
[docs] def invoke(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Output:
return self.bound.invoke(
input,
self._merge_configs(config),
**{**self.kwargs, **kwargs},
)
[docs] async def ainvoke(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Output:
return await self.bound.ainvoke(
input,
self._merge_configs(config),
**{**self.kwargs, **kwargs},
)
[docs] def batch(
self,
inputs: List[Input],
config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
**kwargs: Optional[Any],
) -> List[Output]:
if isinstance(config, list):
configs = cast(
List[RunnableConfig],
[self._merge_configs(conf) for conf in config],
)
else:
configs = [self._merge_configs(config) for _ in range(len(inputs))]
return self.bound.batch(
inputs,
configs,
return_exceptions=return_exceptions,
**{**self.kwargs, **kwargs},
)
[docs] async def abatch(
self,
inputs: List[Input],
config: Optional[Union[RunnableConfig, List[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
**kwargs: Optional[Any],
) -> List[Output]:
if isinstance(config, list):
configs = cast(
List[RunnableConfig],
[self._merge_configs(conf) for conf in config],
)
else:
configs = [self._merge_configs(config) for _ in range(len(inputs))]
return await self.bound.abatch(
inputs,
configs,
return_exceptions=return_exceptions,
**{**self.kwargs, **kwargs},
)
[docs] def stream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Iterator[Output]:
yield from self.bound.stream(
input,
self._merge_configs(config),
**{**self.kwargs, **kwargs},
)
[docs] async def astream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[Output]:
async for item in self.bound.astream(
input,
self._merge_configs(config),
**{**self.kwargs, **kwargs},
):
yield item
RunnableBindingBase.update_forward_refs(RunnableConfig=RunnableConfig)
[docs]class RunnableBinding(RunnableBindingBase[Input, Output]):
"""Wrap a runnable with additional functionality.
A RunnableBinding can be thought of as a "runnable decorator" that
preserves the essential features of Runnable; i.e., batching, streaming,
and async support, while adding additional functionality.
Any class that inherits from Runnable can be bound to a `RunnableBinding`.
Runnables expose a standard set of methods for creating `RunnableBindings`
or sub-classes of `RunnableBindings` (e.g., `RunnableRetry`,
`RunnableWithFallbacks`) that add additional functionality.
These methods include:
- `bind`: Bind kwargs to pass to the underlying runnable when running it.
- `with_config`: Bind config to pass to the underlying runnable when running it.
- `with_listeners`: Bind lifecycle listeners to the underlying runnable.
- `with_types`: Override the input and output types of the underlying runnable.
- `with_retry`: Bind a retry policy to the underlying runnable.
- `with_fallbacks`: Bind a fallback policy to the underlying runnable.
Example:
`bind`: Bind kwargs to pass to the underlying runnable when running it.
.. code-block:: python
# Create a runnable binding that invokes the ChatModel with the
# additional kwarg `stop=['-']` when running it.
from langchain_community.chat_models import ChatOpenAI
model = ChatOpenAI()
model.invoke('Say "Parrot-MAGIC"', stop=['-']) # Should return `Parrot`
# Using it the easy way via `bind` method which returns a new
# RunnableBinding
runnable_binding = model.bind(stop=['-'])
runnable_binding.invoke('Say "Parrot-MAGIC"') # Should return `Parrot`
Can also be done by instantiating a RunnableBinding directly (not recommended):
.. code-block:: python
from langchain_core.runnables import RunnableBinding
runnable_binding = RunnableBinding(
bound=model,
kwargs={'stop': ['-']} # <-- Note the additional kwargs
)
runnable_binding.invoke('Say "Parrot-MAGIC"') # Should return `Parrot`
"""
[docs] @classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
[docs] def bind(self, **kwargs: Any) -> Runnable[Input, Output]:
"""Bind additional kwargs to a Runnable, returning a new Runnable.
Args:
**kwargs: The kwargs to bind to the Runnable.
Returns:
A new Runnable with the same type and config as the original,
but with the additional kwargs bound.
"""
return self.__class__(
bound=self.bound,
config=self.config,
kwargs={**self.kwargs, **kwargs},
custom_input_type=self.custom_input_type,
custom_output_type=self.custom_output_type,
)
[docs] def with_config(
self,
config: Optional[RunnableConfig] = None,
# Sadly Unpack is not well supported by mypy so this will have to be untyped
**kwargs: Any,
) -> Runnable[Input, Output]:
return self.__class__(
bound=self.bound,
kwargs=self.kwargs,
config=cast(RunnableConfig, {**self.config, **(config or {}), **kwargs}),
custom_input_type=self.custom_input_type,
custom_output_type=self.custom_output_type,
)
[docs] def with_listeners(
self,
*,
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.
Args:
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.
Returns:
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.
"""
from langchain_core.tracers.root_listeners import RootListenersTracer
return self.__class__(
bound=self.bound,
kwargs=self.kwargs,
config=self.config,
config_factories=[
lambda config: {
"callbacks": [
RootListenersTracer(
config=config,
on_start=on_start,
on_end=on_end,
on_error=on_error,
)
],
}
],
custom_input_type=self.custom_input_type,
custom_output_type=self.custom_output_type,
)
[docs] def with_types(
self,
input_type: Optional[Union[Type[Input], BaseModel]] = None,
output_type: Optional[Union[Type[Output], BaseModel]] = None,
) -> Runnable[Input, Output]:
return self.__class__(
bound=self.bound,
kwargs=self.kwargs,
config=self.config,
custom_input_type=input_type
if input_type is not None
else self.custom_input_type,
custom_output_type=output_type
if output_type is not None
else self.custom_output_type,
)
[docs] def with_retry(self, **kwargs: Any) -> Runnable[Input, Output]:
return self.__class__(
bound=self.bound.with_retry(**kwargs),
kwargs=self.kwargs,
config=self.config,
)
RunnableLike = Union[
Runnable[Input, Output],
Callable[[Input], Output],
Callable[[Input], Awaitable[Output]],
Callable[[Iterator[Input]], Iterator[Output]],
Callable[[AsyncIterator[Input]], AsyncIterator[Output]],
Mapping[str, Any],
]
[docs]def coerce_to_runnable(thing: RunnableLike) -> Runnable[Input, Output]:
"""Coerce a runnable-like object into a Runnable.
Args:
thing: A runnable-like object.
Returns:
A Runnable.
"""
if isinstance(thing, Runnable):
return thing
elif inspect.isasyncgenfunction(thing) or inspect.isgeneratorfunction(thing):
return RunnableGenerator(thing)
elif callable(thing):
return RunnableLambda(cast(Callable[[Input], Output], thing))
elif isinstance(thing, dict):
return cast(Runnable[Input, Output], RunnableParallel(thing))
else:
raise TypeError(
f"Expected a Runnable, callable or dict."
f"Instead got an unsupported type: {type(thing)}"
)
@overload
def chain(
func: Callable[[Input], Coroutine[Any, Any, Output]],
) -> Runnable[Input, Output]:
...
@overload
def chain(
func: Callable[[Input], Iterator[Output]],
) -> Runnable[Input, Output]:
...
@overload
def chain(
func: Callable[[Input], AsyncIterator[Output]],
) -> Runnable[Input, Output]:
...
@overload
def chain(
func: Callable[[Input], Output],
) -> Runnable[Input, Output]:
...
[docs]def chain(
func: Union[
Callable[[Input], Output],
Callable[[Input], Iterator[Output]],
Callable[[Input], Coroutine[Any, Any, Output]],
Callable[[Input], AsyncIterator[Output]],
],
) -> Runnable[Input, Output]:
"""Decorate a function to make it a Runnable.
Sets the name of the runnable to the name of the function.
Any runnables called by the function will be traced as dependencies.
Args:
func: A callable.
Returns:
A Runnable.
Example:
.. code-block:: python
from langchain_core.runnables import chain
from langchain_core.prompts import PromptTemplate
from langchain.llms import OpenAI
@chain
def my_func(fields):
prompt = PromptTemplate("Hello, {name}!")
llm = OpenAI()
formatted = prompt.invoke(**fields)
for chunk in llm.stream(formatted):
yield chunk
"""
return RunnableLambda(func)