Agents

# Pseudocode
while not done:
    get the model's next thought
    take an action based upon the though
    choose arguments for the selection action
    observe the toll output
    check if a final answer can be obtained
return the final answer

# file: https://github.com/generative-computing/mellea/blob/main/docs/examples/agents/react.py#L99
def react(
    m: mellea.MelleaSession,
    goal: str,
    state_description: str | None,
    react_toolbox: ReactToolbox,
):
    test_ctx_lin = m.ctx.view_for_generation()
    assert test_ctx_lin is not None and len(test_ctx_lin) == 0, (
        "ReACT expects a fresh context."
    )

    # Construct the system prompt for ReACT.
    _sys_prompt = react_system_template.render(
        {"today": datetime.date.today(), "tools": react_toolbox.tools}
    )

    # Add the system prompt and the goal to the chat history.
    m.ctx = m.ctx.add(
        mellea.stdlib.chat.Message(role="system", content=_sys_prompt)
    ).add(mellea.stdlib.chat.Message(role="user", content=f"{goal}"))

    # The main ReACT loop as a dynamic program:
    # (  ?(not done) ;
    #    (thought request ; thought response) ;
    #    (action request ; action response) ;
    #    (action args request ; action args response) ;
    #    observation from the tool call ;
    #    (is done request ; is done response) ;
    #    { ?(model indicated done) ; emit_final_answer ; done := true }
    # )*
    done = False
    turn_num = 0
    while not done:
        turn_num += 1
        print(f"## ReACT TURN NUMBER {turn_num}")

        print("### Thought")
        thought = m.chat(
            "What should you do next? Respond with a description of the next piece of information you need or the next action you need to take."
        )
        print(thought.content)

        print("### Action")
        act = m.chat(
            "Choose your next action. Respond with a nothing other than a tool name.",
            format=react_toolbox.tool_name_schema(),
        )
        selected_tool: ReactTool = react_toolbox.get_tool_from_schema(act.content)
        print(selected_tool.get_name())

        print("### Arguments for action")
        act_args = m.chat(
            "Choose arguments for the tool. Respond using JSON and include only the tool arguments in your response.",
            format=selected_tool.args_schema(),
        )
        print(f"```json\n{json.dumps(json.loads(act_args.content), indent=2)}\n```")

        print("### Observation")
        tool_output = react_toolbox.call_tool(selected_tool, act_args.content)
        m.ctx = m.ctx.add(mellea.stdlib.chat.Message(role="tool", content=tool_output))
        print(tool_output)

        print("### Done Check")
        is_done = IsDoneModel.model_validate_json(
            m.chat(
                f"Do you know the answer to the user's original query ({goal})? If so, respond with Yes. If you need to take more actions, then respond No.",
                format=IsDoneModel,
            ).content
        ).is_done
        if is_done:
            print("Done. Will summarize and return output now.")
            done = True
            return m.chat(
                f"Please provide your final answer to the original query ({goal})."
            ).content
        else:
            print("Not done.")
            done = False

if __name__ == "__main__":
    m = mellea.start_session(ctx=ChatContext())

    # ZIP lookup tool function
    def zip_lookup_tool_fn(city: str):
        """Returns the ZIP code for the `city`."""
        return "03285"

    # convert to tool
    zip_lookup_tool = ReactTool(
        name="Zip Code Lookup",
        fn=zip_lookup_tool_fn,
        description="Returns the ZIP code given a town name.",
    )

    # Weather lookup tool function
    def weather_lookup_fn(zip_code: str):
        """Looks up the weather for a town given a five-digit `zip_code`."""
        return "The weather in Thornton, NH is sunny with a high of 78 and a low of 52. Scattered showers are possible in the afternoon."

    # convert to tool
    weather_lookup_tool = ReactTool(
        name="Get the weather",
        fn=weather_lookup_fn,
        description="Returns the weather given a ZIP code.",
    )

    # use tools for request
    result = react(
        m,
        goal="What is today's high temperature in Thornton, NH?",
        state_description=None,
        react_toolbox=ReactToolbox(tools=[zip_lookup_tool, weather_lookup_tool]),
    )

    print("## Final Answer")
    print(result)

## ReACT TURN NUMBER 1
### Thought
To provide the current weather details for Thornton,
New Hampshire, I first need to obtain its ZIP code
using the "Zip Code Lookup" tool. Once I have the
ZIP code, I will then use the "Get the weather" tool
to find today's high temperature.
### Action
Zip Code Lookup
### Arguments for action
"json
{
  "city": "Thornton, NH"
}"
### Observation
03285
### Done Check
Not done.


## ReACT TURN NUMBER 2
### Thought
I now have Thornton, NH's ZIP code (03285) and need
to use the "Get the weather" tool to find today's
high temperature.

Next step: Utilize the "Get the weather" tool with
the ZIP code for Thornton, New Hampshire.
### Action
Get the weather
### Arguments for action
"json
{
  "zip_code": "03285"
}"
### Observation
The weather in Thornton, NH is sunny with a high of 78
and a low of 52. Scattered showers are possible in
the afternoon.
### Done Check
Done. Will summarize and return output now.

## Final Answer
Today's high temperature in Thornton, New Hampshire is 78 degrees.