base.py — langchain Source File

Source Code

"""Chain for applying constitutional principles to the outputs of another chain."""

from typing import Any

from langchain_core._api import deprecated
from langchain_core.callbacks import CallbackManagerForChainRun
from langchain_core.language_models import BaseLanguageModel
from langchain_core.prompts import BasePromptTemplate

from langchain_classic.chains.base import Chain
from langchain_classic.chains.constitutional_ai.models import ConstitutionalPrinciple
from langchain_classic.chains.constitutional_ai.principles import PRINCIPLES
from langchain_classic.chains.constitutional_ai.prompts import (
    CRITIQUE_PROMPT,
    REVISION_PROMPT,
)
from langchain_classic.chains.llm import LLMChain


@deprecated(
    since="0.2.13",
    message=(
        "This class is deprecated and will be removed in langchain 1.0. "
        "See API reference for replacement: "
        "https://api.python.langchain.com/en/latest/chains/langchain.chains.constitutional_ai.base.ConstitutionalChain.html"
    ),
    removal="1.0",
)
class ConstitutionalChain(Chain):
    r'''Chain for applying constitutional principles.

    !!! note
        This class is deprecated. See below for a replacement implementation using
        LangGraph. The benefits of this implementation are:

        - Uses LLM tool calling features instead of parsing string responses;
        - Support for both token-by-token and step-by-step streaming;
        - Support for checkpointing and memory of chat history;
        - Easier to modify or extend (e.g., with additional tools, structured responses, etc.)

        Install LangGraph with:

        ```bash
        pip install -U langgraph
        ```

        ```python
        from typing import List, Optional, Tuple

        from langchain_classic.chains.constitutional_ai.prompts import (
            CRITIQUE_PROMPT,
            REVISION_PROMPT,
        )
        from langchain_classic.chains.constitutional_ai.models import ConstitutionalPrinciple
        from langchain_core.output_parsers import StrOutputParser
        from langchain_core.prompts import ChatPromptTemplate
        from langchain_openai import ChatOpenAI
        from langgraph.graph import END, START, StateGraph
        from typing_extensions import Annotated, TypedDict

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