paper-gen/react.ts

import { AgentExecutor, ChatAgentOutputParser } from "langchain/agents";
import { formatLogToString } from "langchain/agents/format_scratchpad/log";
import { OpenAI } from "langchain/llms/openai";
import { ChatPromptTemplate, PromptTemplate } from "langchain/prompts";
import { AgentStep } from "langchain/schema";
import { RunnableSequence } from "langchain/schema/runnable";
import { SerpAPI } from "langchain/tools";
import { Calculator } from "langchain/tools/calculator";
import { renderTextDescription } from "langchain/tools/render";
import { llm } from "./llm";
(async function () {
    /** Create a list of the tools we're providing to the agent */
    const tools = [
        new SerpAPI(
            "03647385acfb9e816d2170d07ae7c84131aa4fb6f732b14ffaa34dc065a2f4f6",
            {
                location: "Austin,Texas,United States",
                hl: "en",
                gl: "us",
            }
        ),
        new Calculator(),
    ];

    /**
     * Define our output parser.
     * In this case we'll use the default output parser
     * for chat agents. `ChatAgentOutputParser`
     */
    const outputParser = new ChatAgentOutputParser();

    /**
     * Define our prompts.
     * For this example we'll use the same default prompts
     * that the `ChatAgent` class uses.
     */
    const PREFIX = `Answer the following questions as best you can. You have access to the following tools:
{tools}`;
    const FORMAT_INSTRUCTIONS = `The way you use the tools is by specifying a json blob, denoted below by $JSON_BLOB
Specifically, this $JSON_BLOB should have a "action" key (with the name of the tool to use) and a "action_input" key (with the input to the tool going here). 
The $JSON_BLOB should only contain a SINGLE action, do NOT return a list of multiple actions. Here is an example of a valid $JSON_BLOB:

\`\`\`
{{
  "action": "calculator",
  "action_input": "1 + 2"
}}
\`\`\`

ALWAYS use the following format:

Question: the input question you must answer
Thought: you should always think about what to do
Action: 
\`\`\`
$JSON_BLOB
\`\`\`
Observation: the result of the action
... (this Thought/Action/Observation can repeat N times)
Thought: I now know the final answer
Final Answer: the final answer to the original input question`;
    const SUFFIX = `Begin! Reminder to always use the exact characters \`Final Answer\` when responding.
Thoughts: {agent_scratchpad}`;
    const DEFAULT_HUMAN_MESSAGE_TEMPLATE = "Question: {input}";
    /**
     * Now we can combine all our prompts together, passing
     * in the required input variables.
     */
    // The `renderTextDescription` util function combines
    // all tool names and descriptions into a single string.
    const toolStrings = renderTextDescription(tools);
    const prefixTemplate = PromptTemplate.fromTemplate(PREFIX);
    const formattedPrefix = await prefixTemplate.format({ tools: toolStrings });
    const template = [formattedPrefix, FORMAT_INSTRUCTIONS, SUFFIX].join(
        "\n\n"
    );
    // Add the template, and human message template to an array of messages.
    const prompt = ChatPromptTemplate.fromMessages([
        ["ai", template],
        ["human", DEFAULT_HUMAN_MESSAGE_TEMPLATE],
    ]);

    /**
     * Combine all our previous steps into a runnable agent.
     * We'll use a `RunnableSequence` which takes in an input,
     * and the previous steps. We then format the steps into a
     * string so it can be passed to the prompt.
     */
    const runnableAgent = RunnableSequence.from([
        {
            input: (i: { input: string; steps: AgentStep[] }) => i.input,
            agent_scratchpad: (i: { input: string; steps: AgentStep[] }) =>
                formatLogToString(i.steps),
        },
        prompt,
        llm,
        outputParser,
    ]);

    /**
     * The last step is to pass our agent into the
     * AgentExecutor along with the tools.
     * The AgentExecutor is responsible for actually
     * running the iterations.
     */
    const executor = AgentExecutor.fromAgentAndTools({
        agent: runnableAgent,
        tools,
    });

    console.log("Loaded agent executor");

    const input = `Who is Olivia Wilde's boyfriend? What is his current age raised to the 0.23 power?`;
    console.log(`Calling agent with prompt: ${input}`);
    const result = await executor.call({ input });
    console.log(result);
})();
/**
Loaded agent executor
Calling agent with prompt: Who is Olivia Wilde's boyfriend? What is his current age raised to the 0.23 power?
{
  output: "Jason Sudeikis is Olivia Wilde's boyfriend and his current age raised to the 0.23 power is approximately 1.7."
}
 */