PEP 638 – Syntactic Macros

PEP 638 proposes the introduction of syntactic macros to Python, allowing compile-time functions that transform parts of the program to enhance expressiveness without complicating the language. These macros operate on the program's abstract syntax tree (AST), minimizing errors associated with text-based substitutions and enabling hygienic macros. The motivation behind this proposal stems from the need for modular and distributable language extensions, particularly in rapidly growing fields like data science and machine learning, where core developers may lack domain-specific expertise. By allowing user-defined extensions, the proposal aims to balance the desire for new features with the need to maintain Python's simplicity and learnability. The specification outlines the syntax for defining macros, their compilation process, and the creation of macro processors. It emphasizes the importance of hygiene in variable naming to avoid conflicts and contamination in the original code. Examples illustrate the potential applications of macros in creating compile-time-checked data structures and domain-specific extensions, enhancing the language's flexibility while preserving its core principles.

- PEP 638 introduces syntactic macros to enhance Python's expressiveness.

- Macros operate on the abstract syntax tree, reducing errors from text-based substitutions.

- The proposal aims to allow user-defined extensions without complicating the language.

- Emphasis is placed on hygiene in variable naming to prevent conflicts.

- Examples demonstrate practical applications in data structures and domain-specific programming.