Allow config propagation, Add default lambda name, Improve ergonomics of config passed in (#10273)

Makes it easier to do recursion using regular python compositional
patterns

```py
def lambda_decorator(func):
    """Decorate function as a RunnableLambda"""
    return runnable.RunnableLambda(func)

@lambda_decorator
def fibonacci(a, config: runnable.RunnableConfig) -> int:
    if a <= 1:
        return a
    else:
        return fibonacci.invoke(
            a - 1, config
        ) + fibonacci.invoke(a - 2, config)

fibonacci.invoke(10)
```

https://smith.langchain.com/public/cb98edb4-3a09-4798-9c22-a930037faf88/r

Also makes it more natural to do things like error handle and call other
langchain objects in ways we probably don't want to support in
`with_fallbacks()`

```py
@lambda_decorator
def handle_errors(a, config: runnable.RunnableConfig) -> int:
    try:
        return my_chain.invoke(a, config)
    except MyExceptionType as exc:
        return my_other_chain.invoke({"original": a, "error": exc}, config)
```

In this case, the next chain takes in the exception object. Maybe this
could be something we toggle in `with_fallbacks` but I fear we'll get
into uglier APIs + heavier cognitive load if we try to do too much there

---------

Co-authored-by: Nuno Campos <nuno@boringbits.io>

libs/langchain/langchain/schema/runnable/base.py

@@ -39,6 +39,8 @@ from langchain.load.serializable import Serializable
 from langchain.pydantic_v1 import Field
 from langchain.schema.runnable.config import (
     RunnableConfig,
+    acall_func_with_variable_args,
+    call_func_with_variable_args,
     ensure_config,
     get_async_callback_manager_for_config,
     get_callback_manager_for_config,
@@ -47,16 +49,15 @@ from langchain.schema.runnable.config import (
     patch_config,
 )
 from langchain.schema.runnable.utils import (
+    Input,
+    Output,
+    accepts_config,
     accepts_run_manager,
-    accepts_run_manager_and_config,
     gather_with_concurrency,
 )
 from langchain.utils.aiter import atee, py_anext
 from langchain.utils.iter import safetee
 
-Input = TypeVar("Input")
-# Output type should implement __concat__, as eg str, list, dict do
-Output = TypeVar("Output")
 Other = TypeVar("Other")
 
 
@@ -311,16 +312,7 @@ class Runnable(Generic[Input, Output], ABC):
             name=config.get("run_name"),
         )
         try:
-            if accepts_run_manager_and_config(func):
-                output = func(
-                    input,
-                    run_manager=run_manager,
-                    config=config,
-                )  # type: ignore[call-arg]
-            elif accepts_run_manager(func):
-                output = func(input, run_manager=run_manager)  # type: ignore[call-arg]
-            else:
-                output = func(input)  # type: ignore[call-arg]
+            output = call_func_with_variable_args(func, input, run_manager, config)
         except Exception as e:
             run_manager.on_chain_error(e)
             raise
@@ -353,19 +345,9 @@ class Runnable(Generic[Input, Output], ABC):
             name=config.get("run_name"),
         )
         try:
-            if accepts_run_manager_and_config(func):
-                output = await func(
-                    input,
-                    run_manager=run_manager,
-                    config=config,
-                )  # type: ignore[call-arg]
-            elif accepts_run_manager(func):
-                output = await func(
-                    input,
-                    run_manager=run_manager,
-                )  # type: ignore[call-arg]
-            else:
-                output = await func(input)  # type: ignore[call-arg]
+            output = await acall_func_with_variable_args(
+                func, input, run_manager, config
+            )
         except Exception as e:
             await run_manager.on_chain_error(e)
             raise
@@ -408,16 +390,15 @@ class Runnable(Generic[Input, Output], ABC):
             )
         ]
         try:
-            if accepts_run_manager_and_config(func):
-                output = func(
-                    input,
-                    run_manager=run_managers,
-                    config=configs,
-                )  # type: ignore[call-arg]
-            elif accepts_run_manager(func):
-                output = func(input, run_manager=run_managers)  # type: ignore[call-arg]
-            else:
-                output = func(input)  # type: ignore[call-arg]
+            kwargs: Dict[str, Any] = {}
+            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 Exception as e:
             for run_manager in run_managers:
                 run_manager.on_chain_error(e)
@@ -479,16 +460,15 @@ class Runnable(Generic[Input, Output], ABC):
             )
         )
         try:
-            if accepts_run_manager_and_config(func):
-                output = await func(
-                    input,
-                    run_manager=run_managers,
-                    config=configs,
-                )  # type: ignore[call-arg]
-            elif accepts_run_manager(func):
-                output = await func(input, run_manager=run_managers)  # type: ignore
-            else:
-                output = await func(input)  # type: ignore[call-arg]
+            kwargs: Dict[str, Any] = {}
+            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 Exception as e:
             await asyncio.gather(
                 *(run_manager.on_chain_error(e) for run_manager in run_managers)
@@ -550,19 +530,14 @@ class Runnable(Generic[Input, Output], ABC):
             name=config.get("run_name"),
         )
         try:
-            if accepts_run_manager_and_config(transformer):
-                iterator = transformer(
-                    input_for_transform,
-                    run_manager=run_manager,
-                    config=config,
-                )  # type: ignore[call-arg]
-            elif accepts_run_manager(transformer):
-                iterator = transformer(
-                    input_for_transform,
-                    run_manager=run_manager,
-                )  # type: ignore[call-arg]
-            else:
-                iterator = transformer(input_for_transform)  # type: ignore[call-arg]
+            kwargs: Dict[str, Any] = {}
+            if accepts_config(transformer):
+                kwargs["config"] = patch_config(
+                    config, callbacks=run_manager.get_child()
+                )
+            if accepts_run_manager(transformer):
+                kwargs["run_manager"] = run_manager
+            iterator = transformer(input_for_transform, **kwargs)  # type: ignore[call-arg]
             for chunk in iterator:
                 yield chunk
                 if final_output_supported:
@@ -631,21 +606,14 @@ class Runnable(Generic[Input, Output], ABC):
             name=config.get("run_name"),
         )
         try:
-            # mypy can't quite work out thew type guard here, but this is safe,
-            # check implementations of the accepts_* functions
-            if accepts_run_manager_and_config(transformer):
-                iterator = transformer(
-                    input_for_transform,
-                    run_manager=run_manager,
-                    config=config,
-                )  # type: ignore[call-arg]
-            elif accepts_run_manager(transformer):
-                iterator = transformer(
-                    input_for_transform,
-                    run_manager=run_manager,
-                )  # type: ignore[call-arg]
-            else:
-                iterator = transformer(input_for_transform)  # type: ignore[call-arg]
+            kwargs: Dict[str, Any] = {}
+            if accepts_config(transformer):
+                kwargs["config"] = patch_config(
+                    config, callbacks=run_manager.get_child()
+                )
+            if accepts_run_manager(transformer):
+                kwargs["run_manager"] = run_manager
+            iterator = transformer(input_for_transform, **kwargs)  # type: ignore[call-arg]
             async for chunk in iterator:
                 yield chunk
                 if final_output_supported:
@@ -1756,7 +1724,7 @@ class RunnableLambda(Runnable[Input, Output]):
         run_manager: CallbackManagerForChainRun,
         config: RunnableConfig,
     ) -> Output:
-        output = self.func(input)
+        output = call_func_with_variable_args(self.func, input, run_manager, config)
         # If the output is a runnable, invoke it
         if isinstance(output, Runnable):
             recursion_limit = config["recursion_limit"]
@@ -1780,7 +1748,9 @@ class RunnableLambda(Runnable[Input, Output]):
         run_manager: AsyncCallbackManagerForChainRun,
         config: RunnableConfig,
     ) -> Output:
-        output = await self.afunc(input)
+        output = await acall_func_with_variable_args(
+            self.afunc, input, run_manager, config
+        )
         # If the output is a runnable, invoke it
         if isinstance(output, Runnable):
             recursion_limit = config["recursion_limit"]
@@ -1798,6 +1768,21 @@ class RunnableLambda(Runnable[Input, Output]):
             )
         return output
 
+    def _config(
+        self, config: Optional[RunnableConfig], callable: Callable[..., Any]
+    ) -> RunnableConfig:
+        config = config or {}
+
+        if config.get("run_name") is None:
+            try:
+                run_name = callable.__name__
+            except AttributeError:
+                run_name = None
+            if run_name is not None:
+                return patch_config(config, run_name=run_name)
+
+        return config
+
     def invoke(
         self,
         input: Input,
@@ -1805,7 +1790,11 @@ class RunnableLambda(Runnable[Input, Output]):
         **kwargs: Optional[Any],
     ) -> Output:
         if hasattr(self, "func"):
-            return self._call_with_config(self._invoke, input, config)
+            return self._call_with_config(
+                self._invoke,
+                input,
+                self._config(config, self.func),
+            )
         else:
             raise TypeError(
                 "Cannot invoke a coroutine function synchronously."
@@ -1819,7 +1808,11 @@ class RunnableLambda(Runnable[Input, Output]):
         **kwargs: Optional[Any],
     ) -> Output:
         if hasattr(self, "afunc"):
-            return await self._acall_with_config(self._ainvoke, input, config)
+            return await self._acall_with_config(
+                self._ainvoke,
+                input,
+                self._config(config, self.afunc),
+            )
         else:
             # Delegating to super implementation of ainvoke.
             # Uses asyncio executor to run the sync version (invoke)

libs/langchain/langchain/schema/runnable/config.py

@@ -3,13 +3,35 @@ from __future__ import annotations
 from concurrent.futures import Executor, ThreadPoolExecutor
 from contextlib import contextmanager
 from copy import deepcopy
-from typing import TYPE_CHECKING, Any, Dict, Generator, List, Optional, Union
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Awaitable,
+    Callable,
+    Dict,
+    Generator,
+    List,
+    Optional,
+    Union,
+)
 
 from typing_extensions import TypedDict
 
+from langchain.schema.runnable.utils import (
+    Input,
+    Output,
+    accepts_config,
+    accepts_run_manager,
+)
+
 if TYPE_CHECKING:
     from langchain.callbacks.base import BaseCallbackManager, Callbacks
-    from langchain.callbacks.manager import AsyncCallbackManager, CallbackManager
+    from langchain.callbacks.manager import (
+        AsyncCallbackManager,
+        AsyncCallbackManagerForChainRun,
+        CallbackManager,
+        CallbackManagerForChainRun,
+    )
 
 
 class RunnableConfig(TypedDict, total=False):
@@ -117,6 +139,47 @@ def patch_config(
     return config
 
 
+def call_func_with_variable_args(
+    func: Union[
+        Callable[[Input], Output],
+        Callable[[Input, CallbackManagerForChainRun], Output],
+        Callable[[Input, CallbackManagerForChainRun, RunnableConfig], Output],
+    ],
+    input: Input,
+    run_manager: CallbackManagerForChainRun,
+    config: RunnableConfig,
+) -> Output:
+    """Call function that may optionally accept a run_manager and/or config."""
+    kwargs: Dict[str, Any] = {}
+    if accepts_config(func):
+        kwargs["config"] = patch_config(config, callbacks=run_manager.get_child())
+    if accepts_run_manager(func):
+        kwargs["run_manager"] = run_manager
+    return func(input, **kwargs)  # type: ignore[call-arg]
+
+
+async def acall_func_with_variable_args(
+    func: Union[
+        Callable[[Input], Awaitable[Output]],
+        Callable[[Input, AsyncCallbackManagerForChainRun], Awaitable[Output]],
+        Callable[
+            [Input, AsyncCallbackManagerForChainRun, RunnableConfig],
+            Awaitable[Output],
+        ],
+    ],
+    input: Input,
+    run_manager: AsyncCallbackManagerForChainRun,
+    config: RunnableConfig,
+) -> Output:
+    """Call function that may optionally accept a run_manager and/or config."""
+    kwargs: Dict[str, Any] = {}
+    if accepts_config(func):
+        kwargs["config"] = patch_config(config, callbacks=run_manager.get_child())
+    if accepts_run_manager(func):
+        kwargs["run_manager"] = run_manager
+    return await func(input, **kwargs)  # type: ignore[call-arg]
+
+
 def get_callback_manager_for_config(config: RunnableConfig) -> CallbackManager:
     from langchain.callbacks.manager import CallbackManager
 

libs/langchain/langchain/schema/runnable/utils.py

@@ -2,7 +2,11 @@ from __future__ import annotations
 
 import asyncio
 from inspect import signature
-from typing import Any, Callable, Coroutine, Union
+from typing import Any, Callable, Coroutine, TypeVar, Union
+
+Input = TypeVar("Input")
+# Output type should implement __concat__, as eg str, list, dict do
+Output = TypeVar("Output")
 
 
 async def gated_coro(semaphore: asyncio.Semaphore, coro: Coroutine) -> Any:
@@ -26,8 +30,8 @@ def accepts_run_manager(callable: Callable[..., Any]) -> bool:
         return False
 
 
-def accepts_run_manager_and_config(callable: Callable[..., Any]) -> bool:
-    return (
-        accepts_run_manager(callable)
-        and signature(callable).parameters.get("config") is not None
-    )
+def accepts_config(callable: Callable[..., Any]) -> bool:
+    try:
+        return signature(callable).parameters.get("config") is not None
+    except ValueError:
+        return False

libs/langchain/tests/unit_tests/schema/runnable/test_runnable.py

@@ -948,7 +948,7 @@ async def test_higher_order_lambda_runnable(
     parent_run = next(r for r in tracer.runs if r.parent_run_id is None)
     assert len(parent_run.child_runs) == 2
     router_run = parent_run.child_runs[1]
-    assert router_run.name == "RunnableLambda"
+    assert router_run.name == "router"
     assert len(router_run.child_runs) == 1
     math_run = router_run.child_runs[0]
     assert math_run.name == "RunnableSequence"
@@ -980,7 +980,7 @@ async def test_higher_order_lambda_runnable(
     parent_run = next(r for r in tracer.runs if r.parent_run_id is None)
     assert len(parent_run.child_runs) == 2
     router_run = parent_run.child_runs[1]
-    assert router_run.name == "RunnableLambda"
+    assert router_run.name == "arouter"
     assert len(router_run.child_runs) == 1
     math_run = router_run.child_runs[0]
     assert math_run.name == "RunnableSequence"