Suggestions for extradefs

The following packages have something in common with the package extradefs. The packages are ordered in decreasing similarity.

Package firstline: Print the first line of a paragraph in a different font
Package samples: A collection of Plain TeX coding examples
Package toc: Table of contents macros for Plain TeX
Package redefine: Conditional macro, etc., definitions
Package unouter: Suppress \outer flags in Plain TeX
Package declare: Local register name declarations
Package ifis-macros: Check if a given input string is a number or dimension for TeX
Package plipsum: Lorem ipsum for Plain TeX developers
Package miniltx: An abstract of LaTeX facilities for use with Plain TeX
Package defstring: Define macros as verbatim macros
Package getoptk: Define macros with sophisticated options
Package laps: Zero-width boxes for annotations, etc.
Package font-change: Macros to change text and mathematics fonts in plain TeX
Package bibplain: Simple macros for using BibTeX with Plain TeX
Package mathtime-pln: Plain TeX macros for using MathTime and MathTime Plus
Package plstmary: St. Mary’s Road font support for plain TeX
Package pitex: Documentation macros
Package cdcmd: Expandable conditional commands for LaTeX
Package forloop: Iteration in LaTeX
Package lambdax: Use Lambda expression within LaTeX
Package stack: Tools to define and use stacks
Package wright: Define commands with optional arguments
Package hackalloc: Make allocations local
Package mwrite: Write information to files
Package functional: An intuitive functional programming interface for LaTeX2
Package lt3rawobjects: Objects and proxies in LaTeX3
Package l3packages: High-level LaTeX3 concepts
Package arraysort: Sort arrays (or portions of them)
Package bxenclose: Enclose the document body with some pieces of code
Package beamertools: A collection of programming tools for beamer
Package clistmap: Map and iterate over LaTeX3 clists