pocketflow/docs/prompt

# Example App for text summarization & QA using minillmflow
from minillmflow import Node, BatchNode, Flow, BatchFlow, AsyncNode, AsyncFlow, BatchAsyncFlow
import os

# 1) Implement a simple LLM helper (OpenAI in this example).
def call_LLM(prompt):
    # Users must set an OpenAI API key; can also load from env var, etc.
    openai.api_key = "YOUR_API_KEY_HERE"
    r = openai.ChatCompletion.create(
        model="gpt-4",
        messages=[{"role": "user", "content": prompt}]
    )
    return r.choices[0].message.content

# 2) Create a shared store (dict) for Node/Flow data exchange.
#    This can be replaced with a DB or other storage.
#    Design the structure / schema based on the app requirements.
shared = {"data": {}, "summary": {}}

# 3) Create a Node that loads data from disk into shared['data'].
class LoadData(Node):
    # For compute-intensive operations, do them in prep().
    def prep(self, shared):
        path = "../data/PaulGrahamEssaysLarge"
        for filename in os.listdir(path):
            with open(os.path.join(path, filename), 'r') as f:
                shared['data'][filename] = f.read()
    # If LLM was needed, we'd handle it in exec(). Not needed here.
    # (idempotent so it can be retried if needed)
    def exec(self,shared,prep_res): pass 
    # post() can update shared again or decide the next node (by return the action).
    def post(self,shared,prep_res,exec_res): pass 

load_data = LoadData()
# Run the data-loading node once
load_data.run(shared)

# 4) Create a Node that summarizes a single file using the LLM.
class SummarizeFile(Node):
    def prep(self, shared):
        # Use self.params (which must remain immutable during prep/exec/post).
        # Typically, we only store identifying info in params (e.g., filename).
        content = shared['data'][self.params['filename']]
        return content
    def exec(self, shared, prep_res):
        content = prep_res
        prompt = f"{content} Respond a summary of above in 10 words"
        summary = call_llm(prompt)
        return summary
    def post(self, shared, prep_res, exec_res):
        shared["summary"][self.params['filename']] = exec_res

summarize_file = SummarizeFile()
# For testing, we set params directly on the node.
# In real usage, you'd set them in a Flow or BatchFlow.
summarize_file.set_params({"filename":"addiction.txt"})
summarize_file.run(shared)

# 5) If data is large, we can apply a map-reduce pattern:
#    - MapSummaries(BatchNode) => chunk the file and summarize each chunk
#    - ReduceSummaries(Node)   => combine those chunk-level summaries
class MapSummaries(BatchNode):
    def prep(self, shared):
        content = shared['data'][self.params['filename']]
        chunk_size = 10000
        chunks = [content[i:i+chunk_size] for i in range(0, len(content), chunk_size)]
        # Must return an iterable (list or generator) for a BatchNode.
        return chunks
    def exec(self, shared, prep_res):
        # Each iteration of prep_res corresponds to a single chunk.
        chunk = prep_res
        prompt = f"{chunk} Respond a summary of above in 10 words"
        summary = call_llm(prompt)
        return summary
    def post(self, shared, prep_res, exec_res):
        # exec_res is a list of exec() results (summaries for each chunk).
        combined_summary = [f"{i}. {summary}" for i, summary in enumerate(exec_res)]
        shared["summary"][self.params['filename']] = combined_summary

class ReduceSummaries(Node):
    def prep(self, shared):
        # Retrieve the list of chunk summaries from shared storage
        return shared["summary"][self.params['filename']]
    def exec(self, shared, prep_res):
        combined_summary = prep_res
        prompt = f"{combined_summary} Respond a summary of above in 10 words"
        summary = call_llm(prompt)
        return summary
    def post(self, shared, prep_res, exec_res):
        # Store the combined summary as the final summary for this file.
        shared["summary"][self.params['filename']] = exec_res
        
map_summaries = MapSummaries()
reduce_summaries = ReduceSummaries()
# Link map_summaries to reduce_summaries with an action
# By default, the action is "default" (when post returns None, it takes "default" action)
# This is the same as map_summaries - "default" >> reduce_summaries
map_summaries >> reduce_summaries

# We don't directly call map_summaries.run(shared), 
# because that alone would process only the map step without reduce.

# 6) Instead, create a Flow that starts from map_summaries (a Node) 
#    and automatically includes reduce_summaries. 
#    Note: A Flow can also start from any other Flow or BatchFlow.


file_summary_flow = Flow(start=map_summaries)
# When a flow params is set, it will recursively set its params to all nodes in the flow
file_summary_flow.set_params({"filename":"before.txt"})
file_summary_flow.run(shared)

# 7) Summarize all files using a BatchFlow that reruns file_summary_flow for each file
class SummarizeAllFiles(BatchFlow):
    def prep(self, shared):
        # Return a list of parameters to apply in each flow iteration.
        # Each individual param will be merged with this node's own params 
        # Allowing nesting of multi-level BatchFlow. 
        # E.g., first level diretcory, second level file.
        return [{"filename":filename} for filename in shared['data']]

summarize_all_files = SummarizeAllFiles(start=file_summary_flow)
summarize_all_files.run(shared)


# 8) QA Agent: Find the most relevant file based on summary with actions
#    if no question is asked:
#       (a) end: terminate the flow 
#    if question is asked:
#         if relevant file is found:
#            (b) answer: move to answer node and read the whole file to answer the question
#         if no relevant file is found:
#            (c) retry: retry the process to find the relevant file
class FindRelevantFile(Node):
    def prep(self, shared):
        question = input("Enter a question: ")
        formatted_list = [f"- '{filename}': {shared['summary'][filename]}" 
                         for filename in shared['summary']]
        return question, formatted_list
    def exec(self, shared, prep_res):
        question, formatted_list = prep_res
        if not question:
            return {"think":"no question", "has_relevant":False}
        # Provide a structured YAML output that includes:
        # - The chain of thought
        # - Whether any relevant file was found
        # - The most relevant file if found
        prompt = f"""Question: {question} 
Find the most relevant file from: 
{formatted_list}
If no relevant file, explain why
Respond in yaml without additional information:
think: the question has/has no relevant file ...
has_relevant: true/false
most_relevant: filename"""
        response = call_llm(prompt)
        import yaml
        result = yaml.safe_load(response)
        # Ensure required fields are present
        assert "think" in result
        assert "has_relevant" in result
        assert "most_relevant" in result if result["has_relevant"] else True
        return result
    # handle errors by returning a default response in case of exception after retries
    def process_after_fail(self,shared,prep_res,exc):
        # if not overridden, the default is to throw the exception
        return {"think":"error finding the file", "has_relevant":False}
    def post(self, shared, prep_res, exec_res):
        question, _ = prep_res
        # Decide what to do next based on the results
        if not question:
            print(f"No question asked")
            return "end"
        if exec_res["has_relevant"]:
            # Store the question and most relevant file in shared
            shared["question"] = question
            shared["relevant_file"] = exec_res['most_relevant']
            print(f"Relevant file found: {exec_res['most_relevant']}")
            return "answer"
        else:
            print(f"No relevant file found: {exec_res['think']}")
            return "retry"

class AnswerQuestion(Node):
    def prep(self, shared):
        question = shared['question']
        relevant_file = shared['relevant_file']
        # Read the whole file content
        file_content = shared['data'][relevant_file]
        return question, file_content
    def exec(self, shared, prep_res):
        question, file_content = prep_res
        prompt = f"""Question: {question}
File: {file_content}
Answer the question in 50 words"""
        response = call_llm(prompt)
        return response
    def post(self, shared, prep_res, exec_res):
        print(f"Answer: {exec_res}")

class NoOp(Node):
    pass

# Configure the QA agent with appropriate transitions and retries
find_relevant_file = FindRelevantFile(max_retries=3)
answer_question = AnswerQuestion()
no_op = NoOp()

# Connect the nodes based on the actions they return
find_relevant_file - "answer" >> answer_question >> find_relevant_file
find_relevant_file - "retry" >> find_relevant_file
find_relevant_file - "end" >> no_op

qa_agent = Flow(start=find_relevant_file)
qa_agent.run(shared)


# Above example demonstrates the use of minillmflow
# Next, build another app based on the same principles
# First, given the app's requirements, design the Node/Flow structure
# Then, design the data structure within shared storage, and how it's updated
# Finally, implement the Nodes and Flows to achieve the desired functionality