# Welcome to mypy documentation! Mypy is a static type checker for Python. Type checkers help ensure that you’re using variables and functions in your code correctly. With mypy, add type hints (PEP 484 Python programs, and mypy will warn you when you use those types incorrectly. Python is a dynamic language, so usually you’ll only see errors in your code when you attempt to run it. Mypy is a static checker hints for mypy does not interfere with the way your program would otherwise run. Think of type hints as similar to comments! You can always use the Python interpreter to run your code, even if mypy reports

Mypy Documentation Release 1.8.0 Jukka Dec 21, 2023 Powered by TCPDF (www.tcpdf.org) ## FIRST STEPS Contents 1.1 Getting started ..... 3 1.2 Type hints cheat sheet ..... 8 1.3 Using mypy with 20 Running mypy and managing imports ..... 112 1.21 The mypy command line ..... 119 1.22 The mypy configuration file ..... 133 1.23 Inline configuration ..... 153 1.24 Mypy daemon (mypy server) ..... 154 1.25 Using installed packages ..... 159 1.26 Extending and integrating mypy ..... 161 1.27 Automatic stub generation (stubgen) ..... 165 1.28 Automatic stub testing (stubtest) ..... 167

# Welcome to mypy documentation! Mypy is a static type checker for Python. Type checkers help ensure that you’re using variables and functions in your code correctly. With mypy, add type hints (PEP 484 Python programs, and mypy will warn you when you use those types incorrectly. Python is a dynamic language, so usually you’ll only see errors in your code when you attempt to run it. Mypy is a static checker hints for mypy does not interfere with the way your program would otherwise run. Think of type hints as similar to comments! You can always use the Python interpreter to run your code, even if mypy reports

# Mypy Documentation Release 1.10.0+dev.790e8a73d8671a41cae419b4ea07579bfb2bc292.dirty Jukka Feb 20, 2024 Powered by TCPDF (www.tcpdf.org) ## FIRST STEPS Contents 1.1 Getting started ..... 3 1 1.2 Type hints cheat sheet ..... 8 1.3 Using mypy with an existing codebase ..... 15 1.4 Built-in types ..... 19 1.5 Type inference and type annotations ..... 20 1.6 Kinds of types ..... 24 1 20 Running mypy and managing imports ..... 112 1.21 The mypy command line ..... 119 1.22 The mypy configuration file ..... 134 1.23 Inline configuration ..... 154 1.24 Mypy daemon (mypy server)

## 静态类型的Python PYTHON 30th Lyzh（刘知杭） ## 目录 CONTENTS ➤ 有关类型的概念 使用mypy对Python源代码进行静态分析 代数数据类型 拓展知识 ## 关于类型的一些基本概念 有类型不等于有类型系统 PYTHON 30th 动态语言类型化的必要性 ## 不久前的一个案例 ☀️ ☀️ ☁️ rl = filter(lambda x: 类型系统的分类——声明式类型系统与结构化类型系统 声明类型系统通过名字来检查类型 鸭子类型——一个object，你看它长得像鸭子，行为也像鸭子，那他就是鸭子。 结构类型系统检查类型的形状而非名字 PYTHON 30th ## MYPY与Python标准支持 Python标准——指PEP484和PEP3107 ## PEP 3107 – Function Annotations 由于Python2中缺少缺少注释函数参数和返回 该PEP旨在为类型注释提供标准语法，开放Python代码以简化静态分析和重构，潜在的运行时类型检查，以及（可能在某些情况下）利用类型信息生成代码。 在这些目标中，静态分析是最重要的。这包括对类型检查器（如mypy）的支持，以及提供可由IDE实现的代码重构操作。 虽然这些注释可以在运行时通过 __annotations__ 属性拿到，但在运行时不会进行类型检查。相反，该提案假定存在一个单独的第三方的类型检

x == 2 x == 1.5 Manual migration + tools (2to3, Pylint, Futurize, Modernize, caniusepython3, tox, mypy) 2017: Most Python code still written in “23” 2020: 2.x frozen and unsupported 2023: Still used, x == 2 x == 1.5 Manual migration + tools (2to3, Pylint, Futurize, Modernize, caniusepython3, tox, mypy) 2017: Most Python code still written in “23” 2020: 2.x frozen and unsupported 2023: Still used, x == 2 x == 1.5 Manual migration + tools (2to3, Pylint, Futurize, Modernize, caniusepython3, tox, mypy) 2017: Most Python code still written in “23” 2020: 2.x frozen and unsupported 2023: Still used,

type hints: 使用 mypy 进行静态类型检查 static_type_check.py × static_type_check.py 1 a: int 2 a = 10 3 print(a.upper()) 4 5 def add(a:int, b:str) → int: 6 return a + b (share) → share mypy static_type_check

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f7ac27366/p38_2.jpg) ## 4 下班时在干什么？ 有没有空？ 可以来contribute吗？ 添加一个新的扩展？理由？实际的use case？ 为扩展添加静态检查支持(mypy plugins)? 文档？ ## THANK YOU ![Image](/uploads/documents/6/6/a/5/66a5d6654cb52ba97896404f7ac27366/p39_2

changes - Tornado now includes type annotations compatible with mypy. These annotations will be used when type-checking your application with mypy, and may be usable in editors and other tools. • Tornado now Availability: Unix ``` if sys.platform == "win32": # The exact form of this condition matters to mypy; it understands # if but not assert in this context. raise Exception("fork not available TYPE_CHECKING: # Coroutine wasn't added to typing until 3.5.3, so only import it # when mypy is running and use forward references. from typing import Coroutine # noqa: F401 _ExcInfoTuple =