from __future__ import annotations
import asyncio
import collections
import functools
import inspect
import threading
from abc import ABC, abstractmethod
from concurrent.futures import FIRST_COMPLETED, wait
from contextvars import copy_context
from functools import wraps
from itertools import groupby, tee
from operator import itemgetter
from typing import (
TYPE_CHECKING,
Any,
AsyncGenerator,
AsyncIterator,
Awaitable,
Callable,
Coroutine,
Dict,
Generic,
Iterator,
List,
Mapping,
Optional,
Protocol,
Sequence,
Set,
Tuple,
Type,
TypeVar,
Union,
cast,
overload,
)
from typing_extensions import Literal, get_args
from langchain_core._api import beta_decorator
from langchain_core.load.serializable import (
Serializable,
SerializedConstructor,
SerializedNotImplemented,
)
from langchain_core.pydantic_v1 import BaseModel, Field
from langchain_core.runnables.config import (
RunnableConfig,
_set_config_context,
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,
)
from langchain_core.runnables.graph import Graph
from langchain_core.runnables.schema import StreamEvent
from langchain_core.runnables.utils import (
AddableDict,
AnyConfigurableField,
ConfigurableField,
ConfigurableFieldSpec,
Input,
Output,
accepts_config,
accepts_run_manager,
asyncio_accepts_context,
create_model,
gather_with_concurrency,
get_function_first_arg_dict_keys,
get_function_nonlocals,
get_lambda_source,
get_unique_config_specs,
indent_lines_after_first,
is_async_callable,
is_async_generator,
)
from langchain_core.utils.aiter import aclosing, atee, py_anext
from langchain_core.utils.iter import safetee
from langchain_core.utils.pydantic import is_basemodel_subclass
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.tools import BaseTool
from langchain_core.tracers.log_stream import (
RunLog,
RunLogPatch,
)
from langchain_core.tracers.root_listeners import AsyncListener
from langchain_core.tracers.schemas import Run
Other = TypeVar("Other")
[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!') # noqa: T201
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/
""" # noqa: E501
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 is_basemodel_subclass(root_type):
return root_type
return create_model(
self.get_name("Output"),
__root__=(root_type, None),
)
@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
},
)
if config_specs
else None
)
return create_model( # type: ignore[call-overload]
self.get_name("Config"),
**({"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()
try:
input_node = graph.add_node(self.get_input_schema(config))
except TypeError:
input_node = graph.add_node(create_model(self.get_name("Input")))
runnable_node = graph.add_node(
self, metadata=config.get("metadata") if config else None
)
try:
output_node = graph.add_node(self.get_output_schema(config))
except TypeError:
output_node = graph.add_node(create_model(self.get_name("Output")))
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]:
"""Return a list of prompts used by this Runnable."""
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 Runnable-like objects to make a RunnableSequence.
Equivalent to `RunnableSequence(self, *others)` or `self | others[0] | ...`
Example:
.. 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.pipe(runnable_2)
# Or equivalently:
# sequence = runnable_1 | runnable_2
# sequence = RunnableSequence(first=runnable_1, last=runnable_2)
sequence.invoke(1)
await sequence.ainvoke(1)
# -> 4
sequence.batch([1, 2, 3])
await sequence.abatch([1, 2, 3])
# -> [4, 6, 8]
"""
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.
Pick single key:
.. code-block:: python
import json
from langchain_core.runnables import RunnableLambda, RunnableMap
as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)
chain = RunnableMap(str=as_str, json=as_json)
chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3]}
json_only_chain = chain.pick("json")
json_only_chain.invoke("[1, 2, 3]")
# -> [1, 2, 3]
Pick list of keys:
.. code-block:: python
from typing import Any
import json
from langchain_core.runnables import RunnableLambda, RunnableMap
as_str = RunnableLambda(str)
as_json = RunnableLambda(json.loads)
def as_bytes(x: Any) -> bytes:
return bytes(x, "utf-8")
chain = RunnableMap(
str=as_str,
json=as_json,
bytes=RunnableLambda(as_bytes)
)
chain.invoke("[1, 2, 3]")
# -> {"str": "[1, 2, 3]", "json": [1, 2, 3], "bytes": b"[1, 2, 3]"}
json_and_bytes_chain = chain.pick(["json", "bytes"])
json_and_bytes_chain.invoke("[1, 2, 3]")
# -> {"json": [1, 2, 3], "bytes": b"[1, 2, 3]"}
"""
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.
.. code-block:: python
from langchain_community.llms.fake import FakeStreamingListLLM
from langchain_core.output_parsers import StrOutputParser
from langchain_core.prompts import SystemMessagePromptTemplate
from langchain_core.runnables import Runnable
from operator import itemgetter
prompt = (
SystemMessagePromptTemplate.from_template("You are a nice assistant.")
+ "{question}"
)
llm = FakeStreamingListLLM(responses=["foo-lish"])
chain: Runnable = prompt | llm | {"str": StrOutputParser()}
chain_with_assign = chain.assign(hello=itemgetter("str") | llm)
print(chain_with_assign.input_schema.schema())
# {'title': 'PromptInput', 'type': 'object', 'properties':
{'question': {'title': 'Question', 'type': 'string'}}}
print(chain_with_assign.output_schema.schema()) #
{'title': 'RunnableSequenceOutput', 'type': 'object', 'properties':
{'str': {'title': 'Str',
'type': 'string'}, 'hello': {'title': 'Hello', 'type': 'string'}}}
"""
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)))
@overload
def batch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: Literal[False] = False,
**kwargs: Any,
) -> Iterator[Tuple[int, Output]]: ...
@overload
def batch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: Literal[True],
**kwargs: Any,
) -> Iterator[Tuple[int, Union[Output, Exception]]]: ...
[docs] def batch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
**kwargs: Optional[Any],
) -> Iterator[Tuple[int, Union[Output, Exception]]]:
"""Run invoke in parallel on a list of inputs,
yielding results as they complete."""
if not inputs:
return
configs = get_config_list(config, len(inputs))
def invoke(
i: int, input: Input, config: RunnableConfig
) -> Tuple[int, Union[Output, Exception]]:
if return_exceptions:
try:
out: Union[Output, Exception] = self.invoke(input, config, **kwargs)
except Exception as e:
out = e
else:
out = self.invoke(input, config, **kwargs)
return (i, out)
if len(inputs) == 1:
yield invoke(0, inputs[0], configs[0])
return
with get_executor_for_config(configs[0]) as executor:
futures = {
executor.submit(invoke, i, input, config)
for i, (input, config) in enumerate(zip(inputs, configs))
}
try:
while futures:
done, futures = wait(futures, return_when=FIRST_COMPLETED)
while done:
yield done.pop().result()
finally:
for future in futures:
future.cancel()
[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.
Args:
inputs: A list of inputs 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. Defaults to None.
return_exceptions: Whether to return exceptions instead of raising them.
Defaults to False.
kwargs: Additional keyword arguments to pass to the Runnable.
Returns:
A list of outputs from the Runnable.
"""
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)
@overload
def abatch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: Literal[False] = False,
**kwargs: Optional[Any],
) -> AsyncIterator[Tuple[int, Output]]: ...
@overload
def abatch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: Literal[True],
**kwargs: Optional[Any],
) -> AsyncIterator[Tuple[int, Union[Output, Exception]]]: ...
[docs] async def abatch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
**kwargs: Optional[Any],
) -> AsyncIterator[Tuple[int, Union[Output, Exception]]]:
"""Run ainvoke in parallel on a list of inputs,
yielding results as they complete.
Args:
inputs: A list of inputs 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. Defaults to None. Defaults to None.
return_exceptions: Whether to return exceptions instead of raising them.
Defaults to False.
kwargs: Additional keyword arguments to pass to the Runnable.
Yields:
A tuple of the index of the input and the output from the Runnable.
"""
if not inputs:
return
configs = get_config_list(config, len(inputs))
async def ainvoke(
i: int, input: Input, config: RunnableConfig
) -> Tuple[int, Union[Output, Exception]]:
if return_exceptions:
try:
out: Union[Output, Exception] = await self.ainvoke(
input, config, **kwargs
)
except Exception as e:
out = e
else:
out = await self.ainvoke(input, config, **kwargs)
return (i, out)
coros = map(ainvoke, range(len(inputs)), inputs, configs)
for coro in asyncio.as_completed(coros):
yield await coro
[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.
Args:
input: The input to the Runnable.
config: The config to use for the Runnable. Defaults to None.
kwargs: Additional keyword arguments to pass to the Runnable.
Yields:
The output of the Runnable.
"""
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.
Args:
input: The input to the Runnable.
config: The config to use for the Runnable. Defaults to None.
kwargs: Additional keyword arguments to pass to the Runnable.
Yields:
The output of the Runnable.
"""
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: 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: 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: 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.
kwargs: Additional keyword arguments to pass to the Runnable.
Yields:
A RunLogPatch or RunLog object.
"""
from langchain_core.tracers.log_stream import (
LogStreamCallbackHandler,
_astream_log_implementation,
)
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,
_schema_format="original",
)
# Mypy isn't resolving the overloads here
# Likely an issue b/c `self` is being passed through
# and it's can't map it to Runnable[Input,Output]?
async for item in _astream_log_implementation( # type: ignore
self,
input,
config,
diff=diff,
stream=stream,
with_streamed_output_list=with_streamed_output_list,
**kwargs,
):
yield item
[docs] @beta_decorator.beta(message="This API is in beta and may change in the future.")
async def astream_events(
self,
input: Any,
config: Optional[RunnableConfig] = None,
*,
version: Literal["v1", "v2"],
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: Any,
) -> AsyncIterator[StreamEvent]:
"""Generate a stream of events.
Use to create an iterator over StreamEvents that provide real-time information
about the progress of the Runnable, including StreamEvents from intermediate
results.
A StreamEvent is a dictionary with the following schema:
- ``event``: **str** - Event names are of the
format: on_[runnable_type]_(start|stream|end).
- ``name``: **str** - The name of the Runnable that generated the event.
- ``run_id``: **str** - randomly generated ID associated with the given execution of
the Runnable that emitted the event.
A child Runnable that gets invoked as part of the execution of a
parent Runnable is assigned its own unique ID.
- ``parent_ids``: **List[str]** - The IDs of the parent runnables that
generated the event. The root Runnable will have an empty list.
The order of the parent IDs is from the root to the immediate parent.
Only available for v2 version of the API. The v1 version of the API
will return an empty list.
- ``tags``: **Optional[List[str]]** - The tags of the Runnable that generated
the event.
- ``metadata``: **Optional[Dict[str, Any]]** - The metadata of the Runnable
that generated the event.
- ``data``: **Dict[str, Any]**
Below is a table that illustrates some evens that might be emitted by various
chains. Metadata fields have been omitted from the table for brevity.
Chain definitions have been included after the table.
**ATTENTION** This reference table is for the V2 version of the schema.
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| event | name | chunk | input | output |
+======================+==================+=================================+===============================================+=================================================+
| on_chat_model_start | [model name] | | {"messages": [[SystemMessage, HumanMessage]]} | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_chat_model_stream | [model name] | AIMessageChunk(content="hello") | | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_chat_model_end | [model name] | | {"messages": [[SystemMessage, HumanMessage]]} | AIMessageChunk(content="hello world") |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_llm_start | [model name] | | {'input': 'hello'} | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_llm_stream | [model name] | 'Hello' | | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_llm_end | [model name] | | 'Hello human!' | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_chain_start | format_docs | | | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_chain_stream | format_docs | "hello world!, goodbye world!" | | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_chain_end | format_docs | | [Document(...)] | "hello world!, goodbye world!" |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_tool_start | some_tool | | {"x": 1, "y": "2"} | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_tool_end | some_tool | | | {"x": 1, "y": "2"} |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_retriever_start | [retriever name] | | {"query": "hello"} | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_retriever_end | [retriever name] | | {"query": "hello"} | [Document(...), ..] |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_prompt_start | [template_name] | | {"question": "hello"} | |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
| on_prompt_end | [template_name] | | {"question": "hello"} | ChatPromptValue(messages: [SystemMessage, ...]) |
+----------------------+------------------+---------------------------------+-----------------------------------------------+-------------------------------------------------+
In addition to the standard events, users can also dispatch custom events (see example below).
Custom events will be only be surfaced with in the `v2` version of the API!
A custom event has following format:
+-----------+------+-----------------------------------------------------------------------------------------------------------+
| Attribute | Type | Description |
+===========+======+===========================================================================================================+
| name | str | A user defined name for the event. |
+-----------+------+-----------------------------------------------------------------------------------------------------------+
| data | Any | The data associated with the event. This can be anything, though we suggest making it JSON serializable. |
+-----------+------+-----------------------------------------------------------------------------------------------------------+
Here are declarations associated with the standard events shown above:
`format_docs`:
.. code-block:: python
def format_docs(docs: List[Document]) -> str:
'''Format the docs.'''
return ", ".join([doc.page_content for doc in docs])
format_docs = RunnableLambda(format_docs)
`some_tool`:
.. code-block:: python
@tool
def some_tool(x: int, y: str) -> dict:
'''Some_tool.'''
return {"x": x, "y": y}
`prompt`:
.. code-block:: python
template = ChatPromptTemplate.from_messages(
[("system", "You are Cat Agent 007"), ("human", "{question}")]
).with_config({"run_name": "my_template", "tags": ["my_template"]})
Example:
.. code-block:: python
from langchain_core.runnables import RunnableLambda
async def reverse(s: str) -> str:
return s[::-1]
chain = RunnableLambda(func=reverse)
events = [
event async for event in chain.astream_events("hello", version="v2")
]
# will produce the following events (run_id, and parent_ids
# has been omitted for brevity):
[
{
"data": {"input": "hello"},
"event": "on_chain_start",
"metadata": {},
"name": "reverse",
"tags": [],
},
{
"data": {"chunk": "olleh"},
"event": "on_chain_stream",
"metadata": {},
"name": "reverse",
"tags": [],
},
{
"data": {"output": "olleh"},
"event": "on_chain_end",
"metadata": {},
"name": "reverse",
"tags": [],
},
]
Example: Dispatch Custom Event
.. code-block:: python
from langchain_core.callbacks.manager import (
adispatch_custom_event,
)
from langchain_core.runnables import RunnableLambda, RunnableConfig
import asyncio
async def slow_thing(some_input: str, config: RunnableConfig) -> str:
\"\"\"Do something that takes a long time.\"\"\"
await asyncio.sleep(1) # Placeholder for some slow operation
await adispatch_custom_event(
"progress_event",
{"message": "Finished step 1 of 3"},
config=config # Must be included for python < 3.10
)
await asyncio.sleep(1) # Placeholder for some slow operation
await adispatch_custom_event(
"progress_event",
{"message": "Finished step 2 of 3"},
config=config # Must be included for python < 3.10
)
await asyncio.sleep(1) # Placeholder for some slow operation
return "Done"
slow_thing = RunnableLambda(slow_thing)
async for event in slow_thing.astream_events("some_input", version="v2"):
print(event)
Args:
input: The input to the Runnable.
config: The config to use for the Runnable.
version: The version of the schema to use either `v2` or `v1`.
Users should use `v2`.
`v1` is for backwards compatibility and will be deprecated
in 0.4.0.
No default will be assigned until the API is stabilized.
custom events will only be surfaced in `v2`.
include_names: Only include events from runnables with matching names.
include_types: Only include events from runnables with matching types.
include_tags: Only include events from runnables with matching tags.
exclude_names: Exclude events from runnables with matching names.
exclude_types: Exclude events from runnables with matching types.
exclude_tags: Exclude events from runnables with matching tags.
kwargs: Additional keyword arguments to pass to the Runnable.
These will be passed to astream_log as this implementation
of astream_events is built on top of astream_log.
Yields:
An async stream of StreamEvents.
Raises:
NotImplementedError: If the version is not `v1` or `v2`.
""" # noqa: E501
from langchain_core.tracers.event_stream import (
_astream_events_implementation_v1,
_astream_events_implementation_v2,
)
if version == "v2":
event_stream = _astream_events_implementation_v2(
self,
input,
config=config,
include_names=include_names,
include_types=include_types,
include_tags=include_tags,
exclude_names=exclude_names,
exclude_types=exclude_types,
exclude_tags=exclude_tags,
**kwargs,
)
elif version == "v1":
# First implementation, built on top of astream_log API
# This implementation will be deprecated as of 0.2.0
event_stream = _astream_events_implementation_v1(
self,
input,
config=config,
include_names=include_names,
include_types=include_types,
include_tags=include_tags,
exclude_names=exclude_names,
exclude_types=exclude_types,
exclude_tags=exclude_tags,
**kwargs,
)
else:
raise NotImplementedError(
'Only versions "v1" and "v2" of the schema is currently supported.'
)
async with aclosing(event_stream):
async for event in event_stream:
yield event
[docs] def bind(self, **kwargs: Any) -> Runnable[Input, Output]:
"""
Bind arguments to a Runnable, returning a new Runnable.
Useful when a Runnable in a chain requires an argument that is not
in the output of the previous Runnable or included in the user input.
Args:
kwargs: The arguments to bind to the Runnable.
Returns:
A new Runnable with the arguments bound.
Example:
.. code-block:: python
from langchain_community.chat_models import ChatOllama
from langchain_core.output_parsers import StrOutputParser
llm = ChatOllama(model='llama2')
# Without bind.
chain = (
llm
| StrOutputParser()
)
chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two three four five.'
# With bind.
chain = (
llm.bind(stop=["three"])
| StrOutputParser()
)
chain.invoke("Repeat quoted words exactly: 'One two three four five.'")
# Output is 'One two'
"""
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.
Args:
config: The config to bind to the Runnable.
kwargs: Additional keyword arguments to pass to the Runnable.
Returns:
A new Runnable with the config bound.
"""
return RunnableBinding(
bound=self,
config=cast(
RunnableConfig,
{**(config or {}), **kwargs},
), # type: ignore[misc]
kwargs={},
)
[docs] def with_listeners(
self,
*,
on_start: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = None,
on_end: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = None,
on_error: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = 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.
Args:
on_start: Called before the Runnable starts running. Defaults to None.
on_end: Called after the Runnable finishes running. Defaults to None.
on_error: Called if the Runnable throws an error. Defaults to None.
Returns:
A new Runnable with the listeners bound.
Example:
.. code-block:: python
from langchain_core.runnables import RunnableLambda
from langchain_core.tracers.schemas import Run
import time
def test_runnable(time_to_sleep : int):
time.sleep(time_to_sleep)
def fn_start(run_obj: Run):
print("start_time:", run_obj.start_time)
def fn_end(run_obj: Run):
print("end_time:", run_obj.end_time)
chain = RunnableLambda(test_runnable).with_listeners(
on_start=fn_start,
on_end=fn_end
)
chain.invoke(2)
"""
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_alisteners(
self,
*,
on_start: Optional[AsyncListener] = None,
on_end: Optional[AsyncListener] = None,
on_error: Optional[AsyncListener] = None,
) -> Runnable[Input, Output]:
"""
Bind asynchronous lifecycle listeners to a Runnable, returning a new Runnable.
on_start: Asynchronously called before the Runnable starts running.
on_end: Asynchronously called after the Runnable finishes running.
on_error: Asynchronously called if the Runnable throws an error.
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.
Args:
on_start: Asynchronously called before the Runnable starts running.
Defaults to None.
on_end: Asynchronously called after the Runnable finishes running.
Defaults to None.
on_error: Asynchronously called if the Runnable throws an error.
Defaults to None.
Returns:
A new Runnable with the listeners bound.
Example:
.. code-block:: python
from langchain_core.runnables import RunnableLambda
import time
async def test_runnable(time_to_sleep : int):
print(f"Runnable[{time_to_sleep}s]: starts at {format_t(time.time())}")
await asyncio.sleep(time_to_sleep)
print(f"Runnable[{time_to_sleep}s]: ends at {format_t(time.time())}")
async def fn_start(run_obj : Runnable):
print(f"on start callback starts at {format_t(time.time())}
await asyncio.sleep(3)
print(f"on start callback ends at {format_t(time.time())}")
async def fn_end(run_obj : Runnable):
print(f"on end callback starts at {format_t(time.time())}
await asyncio.sleep(2)
print(f"on end callback ends at {format_t(time.time())}")
runnable = RunnableLambda(test_runnable).with_alisteners(
on_start=fn_start,
on_end=fn_end
)
async def concurrent_runs():
await asyncio.gather(runnable.ainvoke(2), runnable.ainvoke(3))
asyncio.run(concurrent_runs())
Result:
on start callback starts at 2024-05-16T14:20:29.637053+00:00
on start callback starts at 2024-05-16T14:20:29.637150+00:00
on start callback ends at 2024-05-16T14:20:32.638305+00:00
on start callback ends at 2024-05-16T14:20:32.638383+00:00
Runnable[3s]: starts at 2024-05-16T14:20:32.638849+00:00
Runnable[5s]: starts at 2024-05-16T14:20:32.638999+00:00
Runnable[3s]: ends at 2024-05-16T14:20:35.640016+00:00
on end callback starts at 2024-05-16T14:20:35.640534+00:00
Runnable[5s]: ends at 2024-05-16T14:20:37.640169+00:00
on end callback starts at 2024-05-16T14:20:37.640574+00:00
on end callback ends at 2024-05-16T14:20:37.640654+00:00
on end callback ends at 2024-05-16T14:20:39.641751+00:00
"""
from langchain_core.tracers.root_listeners import AsyncRootListenersTracer
return RunnableBinding(
bound=self,
config_factories=[
lambda config: {
"callbacks": [
AsyncRootListenersTracer(
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.
Args:
input_type: The input type to bind to the Runnable. Defaults to None.
output_type: The output type to bind to the Runnable. Defaults to None.
Returns:
A new Runnable with the types bound.
"""
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.
Defaults to (Exception,).
wait_exponential_jitter: Whether to add jitter to the wait
time between retries. Defaults to True.
stop_after_attempt: The maximum number of attempts to make before
giving up. Defaults to 3.
Returns:
A new Runnable that retries the original Runnable on exceptions.
Example:
.. code-block:: python
from langchain_core.runnables import RunnableLambda
count = 0
def _lambda(x: int) -> None:
global count
count = count + 1
if x == 1:
raise ValueError("x is 1")
else:
pass
runnable = RunnableLambda(_lambda)
try:
runnable.with_retry(
stop_after_attempt=2,
retry_if_exception_type=(ValueError,),
).invoke(1)
except ValueError:
pass
assert (count == 2)
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.
Returns:
A new Runnable that maps a list of inputs to a list of outputs.
Example:
.. code-block:: python
from langchain_core.runnables import RunnableLambda
def _lambda(x: int) -> int:
return x + 1
runnable = RunnableLambda(_lambda)
print(runnable.map().invoke([1, 2, 3])) # [2, 3, 4]
"""
return RunnableEach(bound=self)
[docs] def with_fallbacks(
self,
fallbacks: Sequence[Runnable[Input, Output]],
*,
exceptions_to_handle: Tuple[Type[BaseException], ...] = (Exception,),
exception_key: Optional[str] = None,
) -> RunnableWithFallbacksT[Input, Output]:
"""Add fallbacks to a Runnable, returning a new Runnable.
The new Runnable will try the original Runnable, and then each fallback
in order, upon failures.
Args:
fallbacks: A sequence of runnables to try if the original Runnable fails.
exceptions_to_handle: A tuple of exception types to handle.
Defaults to (Exception,).
exception_key: If string is specified then handled exceptions will be passed
to fallbacks as part of the input under the specified key. If None,
exceptions will not be passed to fallbacks. If used, the base Runnable
and its fallbacks must accept a dictionary as input. Defaults to None.
Returns:
A new Runnable that will try the original Runnable, and then each
fallback in order, upon failures.
Example:
.. code-block:: python
from typing import Iterator
from langchain_core.runnables import RunnableGenerator
def _generate_immediate_error(input: Iterator) -> Iterator[str]:
raise ValueError()
yield ""
def _generate(input: Iterator) -> Iterator[str]:
yield from "foo bar"
runnable = RunnableGenerator(_generate_immediate_error).with_fallbacks(
[RunnableGenerator(_generate)]
)
print(''.join(runnable.stream({}))) #foo bar
Args:
fallbacks: A sequence of runnables to try if the original Runnable fails.
exceptions_to_handle: A tuple of exception types to handle.
exception_key: If string is specified then handled exceptions will be passed
to fallbacks as part of the input under the specified key. If None,
exceptions will not be passed to fallbacks. If used, the base Runnable
and its fallbacks must accept a dictionary as input.
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,
exception_key=exception_key,
)
""" --- 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,
serialized: Optional[Dict[str, Any]] = 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(
serialized,
input,
run_type=run_type,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
try:
child_config = patch_config(config, callbacks=run_manager.get_child())
context = copy_context()
context.run(_set_config_context, child_config)
output = cast(
Output,
context.run(
call_func_with_variable_args, # type: ignore[arg-type]
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(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,
serialized: Optional[Dict[str, Any]] = 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(
serialized,
input,
run_type=run_type,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
try:
child_config = patch_config(config, callbacks=run_manager.get_child())
context = copy_context()
context.run(_set_config_context, child_config)
coro = acall_func_with_variable_args(
func, input, config, run_manager, **kwargs
)
if asyncio_accepts_context():
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(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(
None,
input,
run_type=run_type,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
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(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(
None,
input,
run_type=run_type,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
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(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."""
# Mixin that is used by both astream log and astream events implementation
from langchain_core.tracers._streaming import _StreamingCallbackHandler
# 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(
None,
{"input": ""},
run_type=run_type,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
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(_set_config_context, child_config)
iterator = context.run(transformer, input_for_transform, **kwargs) # type: ignore[arg-type]
if stream_handler := next(
(
cast(_StreamingCallbackHandler, h)
for h in run_manager.handlers
# instance check OK here, it's a mixin
if isinstance(h, _StreamingCallbackHandler) # type: ignore[misc]
),
None,
):
# populates streamed_output in astream_log() output if needed
iterator = stream_handler.tap_output_iter(run_manager.run_id, iterator)
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 = chunk
final_output_supported = False
else:
final_output = chunk
except (StopIteration, GeneratorExit):
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 = ichunk
final_input_supported = False
else:
final_input = ichunk
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."""
# Mixin that is used by both astream log and astream events implementation
from langchain_core.tracers._streaming import _StreamingCallbackHandler
# 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(
None,
{"input": ""},
run_type=run_type,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
iterator_ = None
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(_set_config_context, child_config)
iterator_ = context.run(transformer, input_for_transform, **kwargs) # type: ignore[arg-type]
if stream_handler := next(
(
cast(_StreamingCallbackHandler, h)
for h in run_manager.handlers
# instance check OK here, it's a mixin
if isinstance(h, _StreamingCallbackHandler) # type: ignore[misc]
),
None,
):
# populates streamed_output in astream_log() output if needed
iterator = stream_handler.tap_output_aiter(
run_manager.run_id, iterator_
)
else:
iterator = iterator_
try:
while True:
if asyncio_accepts_context():
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 = chunk
final_output_supported = False
else:
final_output = chunk
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 = ichunk
final_input_supported = False
else:
final_input = ichunk
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)
finally:
if iterator_ is not None and hasattr(iterator_, "aclose"):
await iterator_.aclose()
[docs]class RunnableSerializable(Serializable, Runnable[Input, Output]):
"""Runnable that can be serialized to JSON."""
name: Optional[str] = None
"""The name of the Runnable. Used for debugging and tracing."""
[docs] def to_json(self) -> Union[SerializedConstructor, SerializedNotImplemented]:
"""Serialize the Runnable to JSON.
Returns:
A JSON-serializable representation of the Runnable.
"""
dumped = super().to_json()
try:
dumped["name"] = self.get_name()
except Exception:
pass
return dumped
[docs] def configurable_fields(
self, **kwargs: AnyConfigurableField
) -> RunnableSerializable[Input, Output]:
"""Configure particular Runnable fields at runtime.
Args:
**kwargs: A dictionary of ConfigurableField instances to configure.
Returns:
A new Runnable with the fields configured.
.. code-block:: python
from langchain_core.runnables import ConfigurableField
from langchain_openai import ChatOpenAI
model = ChatOpenAI(max_tokens=20).configurable_fields(
max_tokens=ConfigurableField(
id="output_token_number",
name="Max tokens in the output",
description="The maximum number of tokens in the output",
)
)
# max_tokens = 20
print(
"max_tokens_20: ",
model.invoke("tell me something about chess").content
)
# max_tokens = 200
print("max_tokens_200: ", model.with_config(
configurable={"output_token_number": 200}
).invoke("tell me something about chess").content
)
"""
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}: "
f"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]:
"""Configure alternatives for Runnables that can be set at runtime.
Args:
which: The ConfigurableField instance that will be used to select the
alternative.
default_key: The default key to use if no alternative is selected.
Defaults to "default".
prefix_keys: Whether to prefix the keys with the ConfigurableField id.
Defaults to False.
**kwargs: A dictionary of keys to Runnable instances or callables that
return Runnable instances.
Returns:
A new Runnable with the alternatives configured.
.. code-block:: python
from langchain_anthropic import ChatAnthropic
from langchain_core.runnables.utils import ConfigurableField
from langchain_openai import ChatOpenAI
model = ChatAnthropic(
model_name="claude-3-sonnet-20240229"
).configurable_alternatives(
ConfigurableField(id="llm"),
default_key="anthropic",
openai=ChatOpenAI()
)
# uses the default model ChatAnthropic
print(model.invoke("which organization created you?").content)
# uses ChatOpenAI
print(
model.with_config(
configurable={"llm": "openai"}
).invoke("which organization created you?").content
)
"""
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__
},
)
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()
},
},
)
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
},
)
else:
field = prev_output_schema.__fields__[last.keys]
return create_model( # type: ignore[call-overload]
"RunnableSequenceOutput",
__root__=(field.annotation, field.default),
)
return last.get_output_schema(config)
[docs]class RunnableSequence(RunnableSerializable[Input, Output]):
"""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 sequence.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_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('-') # noqa: T201
print(chunk, sep='', flush=True) # noqa: T201
"""
# 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.
name: The name of the Runnable. Defaults to None.
first: The first Runnable in the sequence. Defaults to None.
middle: The middle Runnables in the sequence. Defaults to None.
last: The last Runnable in the sequence. Defaults to None.
Raises:
ValueError: If the sequence has less than 2 steps.
"""
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__( # type: ignore[call-arg]
first=steps_flat[0],
middle=list(steps_flat[1:-1]),
last=steps_flat[-1],
name=name,
)
@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.
Returns:
A list of Runnables.
"""
return [self.first] + self.middle + [self.last]
@classmethod
def is_lc_serializable(cls) -> bool:
"""Check if the object is serializable.
Returns:
True if the object is serializable, False otherwise.
Defaults to True.
"""
return True
class Config:
arbitrary_types_allowed = True
@property
def InputType(self) -> Type[Input]:
"""The type of the input to the Runnable."""
return self.first.InputType
@property
def OutputType(self) -> Type[Output]:
"""The type of the output of the Runnable."""
return self.last.OutputType
def get_input_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
"""Get the input schema of the Runnable.
Args:
config: The config to use. Defaults to None.
Returns:
The input schema of the Runnable.
"""
return _seq_input_schema(self.steps, config)
def get_output_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
"""Get the output schema of the Runnable.
Args:
config: The config to use. Defaults to None.
Returns:
The output schema of the Runnable.
"""
return _seq_output_schema(self.steps, config)
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
"""Get the config specs of the Runnable.
Returns:
The config specs of the Runnable.
"""
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)
def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
"""Get the graph representation of the Runnable.
Args:
config: The config to use. Defaults to None.
Returns:
The graph representation of the Runnable.
Raises:
ValueError: If a Runnable has no first or last node.
"""
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()
step_first_node, _ = graph.extend(step_graph)
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, **kwargs: Any
) -> 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(
None,
input,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
# invoke all steps in sequence
try:
for i, step in enumerate(self.steps):
# mark each step as a child run
config = patch_config(
config, callbacks=run_manager.get_child(f"seq:step:{i+1}")
)
context = copy_context()
context.run(_set_config_context, config)
if i == 0:
input = context.run(step.invoke, input, config, **kwargs)
else:
input = context.run(step.invoke, input, config)
# 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(
None,
input,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
# invoke all steps in sequence
try:
for i, step in enumerate(self.steps):
# mark each step as a child run
config = patch_config(
config, callbacks=run_manager.get_child(f"seq:step:{i+1}")
)
context = copy_context()
context.run(_set_config_context, config)
if i == 0:
part = functools.partial(step.ainvoke, input, config, **kwargs)
else:
part = functools.partial(step.ainvoke, input, config)
if asyncio_accepts_context():
input = await asyncio.create_task(part(), context=context) # type: ignore
else:
input = await asyncio.create_task(part())
# 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(
None,
input,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
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 stepidx == 0 else {}),
)
# 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)
],
return_exceptions=return_exceptions,
**(kwargs if i == 0 else {}),
)
# 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(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(
None,
input,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
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 stepidx == 0 else {}),
)
# 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)
],
return_exceptions=return_exceptions,
**(kwargs if i == 0 else {}),
)
# 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(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,
**kwargs: Any,
) -> 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 idx, step in enumerate(steps):
config = patch_config(
config, callbacks=run_manager.get_child(f"seq:step:{idx+1}")
)
if idx == 0:
final_pipeline = step.transform(final_pipeline, config, **kwargs)
else:
final_pipeline = step.transform(final_pipeline, config)
yield from final_pipeline
async def _atransform(
self,
input: AsyncIterator[Input],
run_manager: AsyncCallbackManagerForChainRun,
config: RunnableConfig,
**kwargs: Any,
) -> 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 idx, step in enumerate(steps):
config = patch_config(
config,
callbacks=run_manager.get_child(f"seq:step:{idx+1}"),
)
if idx == 0:
final_pipeline = step.atransform(final_pipeline, config, **kwargs)
else:
final_pipeline = step.atransform(final_pipeline, config)
async for output in final_pipeline:
yield output
def transform(
self,
input: Iterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Iterator[Output]:
yield from self._transform_stream_with_config(
input,
self._transform,
patch_config(config, run_name=(config or {}).get("run_name") or self.name),
**kwargs,
)
[docs] def stream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Iterator[Output]:
yield from self.transform(iter([input]), config, **kwargs)
async def atransform(
self,
input: AsyncIterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[Output]:
async for chunk in self._atransform_stream_with_config(
input,
self._atransform,
patch_config(config, run_name=(config or {}).get("run_name") or self.name),
**kwargs,
):
yield chunk
[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]]):
"""Runnable that runs a mapping of Runnables in parallel, and returns a mapping
of their outputs.
RunnableParallel is one of the two main composition primitives for the LCEL,
alongside RunnableSequence. It invokes Runnables concurrently, providing the same
input to each.
A RunnableParallel can be instantiated directly or by using a dict literal within a
sequence.
Here is a simple example that uses functions to illustrate the use of
RunnableParallel:
.. 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
def mul_three(x: int) -> int:
return x * 3
runnable_1 = RunnableLambda(add_one)
runnable_2 = RunnableLambda(mul_two)
runnable_3 = RunnableLambda(mul_three)
sequence = runnable_1 | { # this dict is coerced to a RunnableParallel
"mul_two": runnable_2,
"mul_three": runnable_3,
}
# Or equivalently:
# sequence = runnable_1 | RunnableParallel(
# {"mul_two": runnable_2, "mul_three": runnable_3}
# )
# Also equivalently:
# sequence = runnable_1 | RunnableParallel(
# mul_two=runnable_2,
# mul_three=runnable_3,
# )
sequence.invoke(1)
await sequence.ainvoke(1)
sequence.batch([1, 2, 3])
await sequence.abatch([1, 2, 3])
RunnableParallel makes it easy to run Runnables in parallel. In the below example,
we simultaneously stream output from two different Runnables:
.. code-block:: python
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.runnables import RunnableParallel
from langchain_openai import ChatOpenAI
model = ChatOpenAI()
joke_chain = (
ChatPromptTemplate.from_template("tell me a joke about {topic}")
| model
)
poem_chain = (
ChatPromptTemplate.from_template("write a 2-line poem about {topic}")
| model
)
runnable = RunnableParallel(joke=joke_chain, poem=poem_chain)
# Display stream
output = {key: "" for key, _ in runnable.output_schema()}
for chunk in runnable.stream({"topic": "bear"}):
for key in chunk:
output[key] = output[key] + chunk[key].content
print(output) # noqa: T201
"""
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__( # type: ignore[call-arg]
steps__={key: coerce_to_runnable(r) for key, r in merged.items()}
)
@classmethod
def is_lc_serializable(cls) -> bool:
return True
@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
def get_name(
self, suffix: Optional[str] = None, *, name: Optional[str] = None
) -> str:
"""Get the name of the Runnable.
Args:
suffix: The suffix to use. Defaults to None.
name: The name to use. Defaults to None.
Returns:
The name of the Runnable.
"""
name = name or self.name or f"RunnableParallel<{','.join(self.steps__.keys())}>"
return super().get_name(suffix, name=name)
@property
def InputType(self) -> Any:
"""The type of the input to the Runnable."""
for step in self.steps__.values():
if step.InputType:
return step.InputType
return Any
def get_input_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
"""Get the input schema of the Runnable.
Args:
config: The config to use. Defaults to None.
Returns:
The input schema of the Runnable.
"""
if all(
s.get_input_schema(config).schema().get("type", "object") == "object"
for s in self.steps__.values()
):
# This is correct, but pydantic typings/mypy don't think so.
return create_model( # type: ignore[call-overload]
self.get_name("Input"),
**{
k: (v.annotation, v.default)
for step in self.steps__.values()
for k, v in step.get_input_schema(config).__fields__.items()
if k != "__root__"
},
)
return super().get_input_schema(config)
def get_output_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
"""Get the output schema of the Runnable.
Args:
config: The config to use. Defaults to None.
Returns:
The output schema of the Runnable.
"""
# 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()},
)
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
"""Get the config specs of the Runnable.
Returns:
The config specs of the Runnable.
"""
return get_unique_config_specs(
spec for step in self.steps__.values() for spec in step.config_specs
)
def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
"""Get the graph representation of the Runnable.
Args:
config: The config to use. Defaults to None.
Returns:
The graph representation of the Runnable.
Raises:
ValueError: If a Runnable has no first or last node.
"""
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:
step_first_node, step_last_node = graph.extend(step_graph)
if not step_first_node:
raise ValueError(f"Runnable {step} has no first 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(
None,
input,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
def _invoke_step(
step: Runnable[Input, Any], input: Input, config: RunnableConfig, key: str
) -> Any:
child_config = patch_config(
config,
# mark each step as a child run
callbacks=run_manager.get_child(f"map:key:{key}"),
)
context = copy_context()
context.run(_set_config_context, child_config)
return context.run(
step.invoke,
input,
child_config,
)
# 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(_invoke_step, step, input, config, 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(
None,
input,
name=config.get("run_name") or self.get_name(),
run_id=config.pop("run_id", None),
)
async def _ainvoke_step(
step: Runnable[Input, Any], input: Input, config: RunnableConfig, key: str
) -> Any:
child_config = patch_config(
config,
callbacks=run_manager.get_child(f"map:key:{key}"),
)
context = copy_context()
context.run(_set_config_context, child_config)
if asyncio_accepts_context():
return await asyncio.create_task( # type: ignore
step.ainvoke(input, child_config), context=context
)
else:
return await asyncio.create_task(step.ainvoke(input, child_config))
# 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(
*(
_ainvoke_step(
step,
input,
# mark each step as a child run
config,
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
def transform(
self,
input: Iterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Iterator[Dict[str, Any]]:
yield from self._transform_stream_with_config(
input, self._transform, config, **kwargs
)
[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
async def atransform(
self,
input: AsyncIterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> AsyncIterator[Dict[str, Any]]:
async for chunk in self._atransform_stream_with_config(
input, self._atransform, config, **kwargs
):
yield chunk
[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]):
"""Runnable that runs a generator function.
RunnableGenerators can be instantiated directly or by using a generator within
a sequence.
RunnableGenerators can be used to implement custom behavior, such as custom output
parsers, while preserving streaming capabilities. Given a generator function with
a signature Iterator[A] -> Iterator[B], wrapping it in a RunnableGenerator allows
it to emit output chunks as soon as they are streamed in from the previous step.
Note that if a generator function has a signature A -> Iterator[B], such that it
requires its input from the previous step to be completed before emitting chunks
(e.g., most LLMs need the entire prompt available to start generating), it can
instead be wrapped in a RunnableLambda.
Here is an example to show the basic mechanics of a RunnableGenerator:
.. code-block:: python
from typing import Any, AsyncIterator, Iterator
from langchain_core.runnables import RunnableGenerator
def gen(input: Iterator[Any]) -> Iterator[str]:
for token in ["Have", " a", " nice", " day"]:
yield token
runnable = RunnableGenerator(gen)
runnable.invoke(None) # "Have a nice day"
list(runnable.stream(None)) # ["Have", " a", " nice", " day"]
runnable.batch([None, None]) # ["Have a nice day", "Have a nice day"]
# Async version:
async def agen(input: AsyncIterator[Any]) -> AsyncIterator[str]:
for token in ["Have", " a", " nice", " day"]:
yield token
runnable = RunnableGenerator(agen)
await runnable.ainvoke(None) # "Have a nice day"
[p async for p in runnable.astream(None)] # ["Have", " a", " nice", " day"]
RunnableGenerator makes it easy to implement custom behavior within a streaming
context. Below we show an example:
.. code-block:: python
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.runnables import RunnableGenerator, RunnableLambda
from langchain_openai import ChatOpenAI
from langchain_core.output_parsers import StrOutputParser
model = ChatOpenAI()
chant_chain = (
ChatPromptTemplate.from_template("Give me a 3 word chant about {topic}")
| model
| StrOutputParser()
)
def character_generator(input: Iterator[str]) -> Iterator[str]:
for token in input:
if "," in token or "." in token:
yield "👏" + token
else:
yield token
runnable = chant_chain | character_generator
assert type(runnable.last) is RunnableGenerator
"".join(runnable.stream({"topic": "waste"})) # Reduce👏, Reuse👏, Recycle👏.
# Note that RunnableLambda can be used to delay streaming of one step in a
# sequence until the previous step is finished:
def reverse_generator(input: str) -> Iterator[str]:
# Yield characters of input in reverse order.
for character in input[::-1]:
yield character
runnable = chant_chain | RunnableLambda(reverse_generator)
"".join(runnable.stream({"topic": "waste"})) # ".elcycer ,esuer ,ecudeR"
"""
def __init__(
self,
transform: Union[
Callable[[Iterator[Input]], Iterator[Output]],
Callable[[AsyncIterator[Input]], AsyncIterator[Output]],
],
atransform: Optional[
Callable[[AsyncIterator[Input]], AsyncIterator[Output]]
] = None,
) -> None:
"""Initialize a RunnableGenerator.
Args:
transform: The transform function.
atransform: The async transform function. Defaults to None.
Raises:
TypeError: If the transform is not a generator function.
"""
if atransform is not None:
self._atransform = atransform
func_for_name: Callable = atransform
if is_async_generator(transform):
self._atransform = transform # type: ignore[assignment]
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 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 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:
return f"RunnableGenerator({self.name})"
def transform(
self,
input: Iterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Iterator[Output]:
if not hasattr(self, "_transform"):
raise NotImplementedError(f"{repr(self)} only supports async methods.")
return self._transform_stream_with_config(
input,
self._transform, # type: ignore[arg-type]
config,
**kwargs, # type: ignore[arg-type]
)
def stream(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Iterator[Output]:
return self.transform(iter([input]), config, **kwargs)
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)
def atransform(
self,
input: AsyncIterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> AsyncIterator[Output]:
if not hasattr(self, "_atransform"):
raise NotImplementedError(f"{repr(self)} only supports sync methods.")
return self._atransform_stream_with_config(
input, self._atransform, config, **kwargs
)
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)
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.
``RunnableLambda`` is best suited for code that does not need to support
streaming. If you need to support streaming (i.e., be able to operate
on chunks of inputs and yield chunks of outputs), use ``RunnableGenerator``
instead.
Note that if a ``RunnableLambda`` returns an instance of ``Runnable``, that
instance is invoked (or streamed) during execution.
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
"""
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,
name: Optional[str] = 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.
Defaults to None.
name: The name of the Runnable. Defaults to None.
Raises:
TypeError: If the func is not a callable type.
TypeError: If both func and afunc are provided.
"""
if afunc is not None:
self.afunc = afunc
func_for_name: Callable = afunc
if is_async_callable(func) or is_async_generator(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 name is not None:
self.name = name
elif 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 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
def get_input_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
"""The pydantic schema for the input to this Runnable.
Args:
config: The config to use. Defaults to None.
Returns:
The input schema for this Runnable.
"""
func = getattr(self, "func", None) or self.afunc
if isinstance(func, itemgetter):
# This is terrible, but afaict it's not possible to access _items
# on itemgetter objects, so we have to parse the repr
items = str(func).replace("operator.itemgetter(", "")[:-1].split(", ")
if all(
item[0] == "'" and item[-1] == "'" and len(item) > 2 for item in items
):
# It's a dict, lol
return create_model(
self.get_name("Input"),
**{item[1:-1]: (Any, None) for item in items}, # type: ignore
)
else:
return create_model(
self.get_name("Input"),
__root__=(List[Any], None),
)
if self.InputType != Any:
return super().get_input_schema(config)
if dict_keys := get_function_first_arg_dict_keys(func):
return create_model(
self.get_name("Input"),
**{key: (Any, None) for key in dict_keys}, # type: ignore
)
return super().get_input_schema(config)
@property
def OutputType(self) -> Any:
"""The type of the output of this Runnable as a type annotation.
Returns:
The type of the output of this Runnable.
"""
func = getattr(self, "func", None) or 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.
Returns:
The dependencies of this Runnable. If the function has nonlocal
variables that are Runnables, they are considered dependencies.
"""
if hasattr(self, "func"):
objects = get_function_nonlocals(self.func)
elif hasattr(self, "afunc"):
objects = get_function_nonlocals(self.afunc)
else:
objects = []
deps: List[Runnable] = []
for obj in objects:
if isinstance(obj, Runnable):
deps.append(obj)
elif isinstance(getattr(obj, "__self__", None), Runnable):
deps.append(obj.__self__)
return deps
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
return get_unique_config_specs(
spec for dep in self.deps for spec in dep.config_specs
)
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:
dep_first_node, dep_last_node = graph.extend(dep_graph)
if not dep_first_node:
raise ValueError(f"Runnable {dep} has no first 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,
**kwargs: Any,
) -> 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,
**kwargs: Any,
) -> 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 is_async_generator(afunc):
output: Optional[Output] = None
async with aclosing(
cast(
AsyncGenerator[Any, Any],
acall_func_with_variable_args(
cast(Callable, afunc),
input,
config,
run_manager,
**kwargs,
),
)
) as stream:
async for chunk in cast(
AsyncIterator[Output],
stream,
):
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:
return ensure_config(config)
def invoke(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Output:
"""Invoke this Runnable synchronously.
Args:
input: The input to this Runnable.
config: The config to use. Defaults to None.
kwargs: Additional keyword arguments.
Returns:
The output of this Runnable.
Raises:
TypeError: If the Runnable is a coroutine function.
"""
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."
)
async def ainvoke(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Output:
"""Invoke this Runnable asynchronously.
Args:
input: The input to this Runnable.
config: The config to use. Defaults to None.
kwargs: Additional keyword arguments.
Returns:
The output of this Runnable.
"""
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: Input
got_first_val = False
for ichunk in input:
# By definitions, RunnableLambdas consume all input before emitting output.
# If the input is not addable, then we'll assume that we can
# only operate on the last chunk.
# So we'll iterate until we get to the last chunk!
if not got_first_val:
final = ichunk
got_first_val = True
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)
def transform(
self,
input: Iterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> Iterator[Output]:
if hasattr(self, "func"):
yield from self._transform_stream_with_config(
input,
self._transform,
self._config(config, self.func),
**kwargs,
)
else:
raise TypeError(
"Cannot stream a coroutine function synchronously."
"Use `astream` instead."
)
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: Input
got_first_val = False
async for ichunk in input:
# By definitions, RunnableLambdas consume all input before emitting output.
# If the input is not addable, then we'll assume that we can
# only operate on the last chunk.
# So we'll iterate until we get to the last chunk!
if not got_first_val:
final = ichunk
got_first_val = True
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,
**kwargs: Any,
) -> 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 is_async_generator(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 is_async_generator(afunc):
# Otherwise, just yield it
yield cast(Output, output)
async def atransform(
self,
input: AsyncIterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[Output]:
async for output in self._atransform_stream_with_config(
input,
self._atransform,
self._config(config, self.afunc if hasattr(self, "afunc") else self.func),
**kwargs,
):
yield output
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]]):
"""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.
See documentation for RunnableEach for more details.
"""
bound: Runnable[Input, Output]
class Config:
arbitrary_types_allowed = True
@property
def InputType(self) -> Any:
return List[self.bound.InputType] # type: ignore[name-defined]
def get_input_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
return create_model(
self.get_name("Input"),
__root__=(
List[self.bound.get_input_schema(config)], # type: ignore
None,
),
)
@property
def OutputType(self) -> Type[List[Output]]:
return List[self.bound.OutputType] # type: ignore[name-defined]
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,
),
)
@property
def config_specs(self) -> List[ConfigurableFieldSpec]:
return self.bound.config_specs
def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
return self.bound.get_graph(config)
@classmethod
def is_lc_serializable(cls) -> bool:
return True
@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]:
configs = [
patch_config(config, callbacks=run_manager.get_child()) for _ in inputs
]
return self.bound.batch(inputs, configs, **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]:
configs = [
patch_config(config, callbacks=run_manager.get_child()) for _ in inputs
]
return await self.bound.abatch(inputs, configs, **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] async def astream_events(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[StreamEvent]:
for _ in range(1):
raise NotImplementedError(
"RunnableEach does not support astream_events yet."
)
yield
[docs]class RunnableEach(RunnableEachBase[Input, Output]):
"""Runnable that delegates calls to another Runnable
with each element of the input sequence.
It allows you to call multiple inputs with the bounded Runnable.
RunnableEach makes it easy to run multiple inputs for the Runnable.
In the below example, we associate and run three inputs
with a Runnable:
.. code-block:: python
from langchain_core.runnables.base import RunnableEach
from langchain_openai import ChatOpenAI
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.output_parsers import StrOutputParser
prompt = ChatPromptTemplate.from_template("Tell me a short joke about
{topic}")
model = ChatOpenAI()
output_parser = StrOutputParser()
runnable = prompt | model | output_parser
runnable_each = RunnableEach(bound=runnable)
output = runnable_each.invoke([{'topic':'Computer Science'},
{'topic':'Art'},
{'topic':'Biology'}])
print(output) # noqa: T201
"""
@classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
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)
def bind(self, **kwargs: Any) -> RunnableEach[Input, Output]:
return RunnableEach(bound=self.bound.bind(**kwargs))
def with_config(
self, config: Optional[RunnableConfig] = None, **kwargs: Any
) -> RunnableEach[Input, Output]:
return RunnableEach(bound=self.bound.with_config(config, **kwargs))
def with_listeners(
self,
*,
on_start: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = None,
on_end: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = None,
on_error: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = None,
) -> RunnableEach[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.
Defaults to None.
on_end: Called after the Runnable finishes running, with the Run object.
Defaults to None.
on_error: Called if the Runnable throws an error, with the Run object.
Defaults to None.
Returns:
A new Runnable with the listeners bound.
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
)
)
def with_alisteners(
self,
*,
on_start: Optional[AsyncListener] = None,
on_end: Optional[AsyncListener] = None,
on_error: Optional[AsyncListener] = None,
) -> RunnableEach[Input, Output]:
"""Bind async lifecycle listeners to a Runnable, returning a new Runnable.
Args:
on_start: Called asynchronously before the Runnable starts running,
with the Run object. Defaults to None.
on_end: Called asynchronously after the Runnable finishes running,
with the Run object. Defaults to None.
on_error: Called asynchronously if the Runnable throws an error,
with the Run object. Defaults to None.
Returns:
A new Runnable with the listeners bound.
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_alisteners(
on_start=on_start, on_end=on_end, on_error=on_error
)
)
[docs]class RunnableBindingBase(RunnableSerializable[Input, Output]):
"""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)
Defaults to None.
config: optional config to bind to the underlying Runnable.
Defaults to None.
config_factories: optional list of config factories to apply to the
config before binding to the underlying Runnable.
Defaults to None.
custom_input_type: Specify to override the input type of the underlying
Runnable with a custom type. Defaults to None.
custom_output_type: Specify to override the output type of the underlying
Runnable with a custom type. Defaults to None.
**other_kwargs: Unpacked into the base class.
"""
super().__init__( # type: ignore[call-arg]
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,
)
# if we don't explicitly set config to the TypedDict here,
# the pydantic init above will strip out any of the "extra"
# fields even though total=False on the typed dict.
self.config = config or {}
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
)
def get_input_schema(
self, config: Optional[RunnableConfig] = None
) -> Type[BaseModel]:
if self.custom_input_type is not None:
return super().get_input_schema(config)
return self.bound.get_input_schema(merge_configs(self.config, config))
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
def get_graph(self, config: Optional[RunnableConfig] = None) -> Graph:
return self.bound.get_graph(self._merge_configs(config))
@classmethod
def is_lc_serializable(cls) -> bool:
return True
@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},
)
@overload
def batch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: Literal[False] = False,
**kwargs: Any,
) -> Iterator[Tuple[int, Output]]: ...
@overload
def batch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: Literal[True],
**kwargs: Any,
) -> Iterator[Tuple[int, Union[Output, Exception]]]: ...
[docs] def batch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
**kwargs: Optional[Any],
) -> Iterator[Tuple[int, Union[Output, Exception]]]:
if isinstance(config, Sequence):
configs = cast(
List[RunnableConfig],
[self._merge_configs(conf) for conf in config],
)
else:
configs = [self._merge_configs(config) for _ in range(len(inputs))]
# lol mypy
if return_exceptions:
yield from self.bound.batch_as_completed(
inputs,
configs,
return_exceptions=return_exceptions,
**{**self.kwargs, **kwargs},
)
else:
yield from self.bound.batch_as_completed(
inputs,
configs,
return_exceptions=return_exceptions,
**{**self.kwargs, **kwargs},
)
@overload
def abatch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: Literal[False] = False,
**kwargs: Optional[Any],
) -> AsyncIterator[Tuple[int, Output]]: ...
@overload
def abatch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: Literal[True],
**kwargs: Optional[Any],
) -> AsyncIterator[Tuple[int, Union[Output, Exception]]]: ...
[docs] async def abatch_as_completed(
self,
inputs: Sequence[Input],
config: Optional[Union[RunnableConfig, Sequence[RunnableConfig]]] = None,
*,
return_exceptions: bool = False,
**kwargs: Optional[Any],
) -> AsyncIterator[Tuple[int, Union[Output, Exception]]]:
if isinstance(config, Sequence):
configs = cast(
List[RunnableConfig],
[self._merge_configs(conf) for conf in config],
)
else:
configs = [self._merge_configs(config) for _ in range(len(inputs))]
if return_exceptions:
async for item in self.bound.abatch_as_completed(
inputs,
configs,
return_exceptions=return_exceptions,
**{**self.kwargs, **kwargs},
):
yield item
else:
async for item in self.bound.abatch_as_completed(
inputs,
configs,
return_exceptions=return_exceptions,
**{**self.kwargs, **kwargs},
):
yield item
[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
[docs] async def astream_events(
self,
input: Input,
config: Optional[RunnableConfig] = None,
**kwargs: Optional[Any],
) -> AsyncIterator[StreamEvent]:
async for item in self.bound.astream_events(
input, self._merge_configs(config), **{**self.kwargs, **kwargs}
):
yield item
def transform(
self,
input: Iterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> Iterator[Output]:
yield from self.bound.transform(
input,
self._merge_configs(config),
**{**self.kwargs, **kwargs},
)
async def atransform(
self,
input: AsyncIterator[Input],
config: Optional[RunnableConfig] = None,
**kwargs: Any,
) -> AsyncIterator[Output]:
async for item in self.bound.atransform(
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`
"""
@classmethod
def get_lc_namespace(cls) -> List[str]:
"""Get the namespace of the langchain object."""
return ["langchain", "schema", "runnable"]
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,
)
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,
)
def with_listeners(
self,
*,
on_start: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = None,
on_end: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = None,
on_error: Optional[
Union[Callable[[Run], None], Callable[[Run, RunnableConfig], None]]
] = 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.
Defaults to None.
on_end: Called after the Runnable finishes running, with the Run object.
Defaults to None.
on_error: Called if the Runnable throws an error, with the Run object.
Defaults to None.
Returns:
The Runnable 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,
)
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
),
)
def with_retry(self, **kwargs: Any) -> Runnable[Input, Output]:
return self.__class__(
bound=self.bound.with_retry(**kwargs),
kwargs=self.kwargs,
config=self.config,
)
def __getattr__(self, name: str) -> Any:
attr = getattr(self.bound, name)
if callable(attr) and (
config_param := inspect.signature(attr).parameters.get("config")
):
if config_param.kind == inspect.Parameter.KEYWORD_ONLY:
@wraps(attr)
def wrapper(*args: Any, **kwargs: Any) -> Any:
return attr(
*args,
config=merge_configs(self.config, kwargs.pop("config", None)),
**kwargs,
)
return wrapper
elif config_param.kind == inspect.Parameter.POSITIONAL_OR_KEYWORD:
idx = list(inspect.signature(attr).parameters).index("config")
@wraps(attr)
def wrapper(*args: Any, **kwargs: Any) -> Any:
if len(args) >= idx + 1:
argsl = list(args)
argsl[idx] = merge_configs(self.config, argsl[idx])
return attr(*argsl, **kwargs)
else:
return attr(
*args,
config=merge_configs(
self.config, kwargs.pop("config", None)
),
**kwargs,
)
return wrapper
return attr
class _RunnableCallableSync(Protocol[Input, Output]):
def __call__(self, __in: Input, *, config: RunnableConfig) -> Output: ...
class _RunnableCallableAsync(Protocol[Input, Output]):
def __call__(self, __in: Input, *, config: RunnableConfig) -> Awaitable[Output]: ...
class _RunnableCallableIterator(Protocol[Input, Output]):
def __call__(
self, __in: Iterator[Input], *, config: RunnableConfig
) -> Iterator[Output]: ...
class _RunnableCallableAsyncIterator(Protocol[Input, Output]):
def __call__(
self, __in: AsyncIterator[Input], *, config: RunnableConfig
) -> AsyncIterator[Output]: ...
RunnableLike = Union[
Runnable[Input, Output],
Callable[[Input], Output],
Callable[[Input], Awaitable[Output]],
Callable[[Iterator[Input]], Iterator[Output]],
Callable[[AsyncIterator[Input]], AsyncIterator[Output]],
_RunnableCallableSync[Input, Output],
_RunnableCallableAsync[Input, Output],
_RunnableCallableIterator[Input, Output],
_RunnableCallableAsyncIterator[Input, 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.
Raises:
TypeError: If the object is not Runnable-like.
"""
if isinstance(thing, Runnable):
return thing
elif is_async_generator(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_openai 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)
