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Module 03 Refactoring Guide

Concept Position

flowchart TD
  family["Python Programming"] --> program["Python Functional Programming"]
  program --> module["Module 03: Iterators, Laziness, and Streaming Dataflow"]
  module --> concept["Module 03 Refactoring Guide"]
  concept --> capstone["Capstone pressure point"]
flowchart TD
  problem["Start with the design or failure question"] --> example["Study the worked example and trade-offs"]
  example --> boundary["Name the boundary this page is trying to protect"]
  boundary --> proof["Carry that question into code review or the capstone"]

Read the first diagram as a placement map: this page is one concept inside its parent module, not a detached essay, and the capstone is the pressure test for whether the idea holds. Read the second diagram as the working rhythm for the page: name the problem, study the example, identify the boundary, then carry one review question forward.

This guide closes Module 03. The point is not to celebrate generators on their own. The point is to know when computation happens, when memory grows, and how to observe a stream without quietly destroying laziness.

Stable comparison route

  1. run make PROGRAM=python-programming/python-functional-programming history-refresh
  2. open capstone/_history/worktrees/module-03/src/funcpipe_rag/
  3. compare the streaming helpers in api/core.py, pipeline_stages.py, and related iterator utilities
  4. read capstone/_history/worktrees/module-03/tests/test_streaming.py

What to refactor toward

  • iterators and generators that expose demand clearly
  • bounded chunking and fan-out choices that are visible in code and tests
  • observability helpers that wrap streams without mutating yielded values
  • explicit materialization points with a stated reason

Exit standard

Before Module 04, you should be able to explain where work starts, where it pauses, and which tests prove that the stream contract survives refactoring.