__init__.py — langchain Source File

Source Code

"""LangChain **Runnable** and the **LangChain Expression Language (LCEL)**.

The LangChain Expression Language (LCEL) offers a declarative method to build
production-grade programs that harness the power of LLMs.

Programs created using LCEL and LangChain `Runnable` objects inherently suppor
synchronous asynchronous, batch, and streaming operations.

Support for **async** allows servers hosting LCEL based programs to scale bette for
higher concurrent loads.

**Batch** operations allow for processing multiple inputs in parallel.

**Streaming** of intermediate outputs, as they're being generated, allows for creating
more responsive UX.

This module contains schema and implementation of LangChain `Runnable` object
primitives.
"""

from typing import TYPE_CHECKING

from langchain_core._import_utils import import_attr

if TYPE_CHECKING:
    from langchain_core.runnables.base import (
        Runnable,
        RunnableBinding,
        RunnableGenerator,
        RunnableLambda,
        RunnableMap,
        RunnableParallel,
        RunnableSequence,
        RunnableSerializable,
        chain,
    )
    from langchain_core.runnables.branch import RunnableBranch
    from langchain_core.runnables.config import (
        RunnableConfig,
        ensure_config,
        get_config_list,
        patch_config,
        run_in_executor,
    )
    from langchain_core.runnables.fallbacks import RunnableWithFallbacks
    from langchain_core.runnables.history import RunnableWithMessageHistory
    from langchain_core.runnables.passthrough import (
        RunnableAssign,
        RunnablePassthrough,
        RunnablePick,
    )
    from langchain_core.runnables.router import RouterInput, RouterRunnable
    from langchain_core.runnables.utils import (
        AddableDict,
        ConfigurableField,
        ConfigurableFieldMultiOption,
        ConfigurableFieldSingleOption,
        ConfigurableFieldSpec,
        aadd,
        add,
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