Suggestions for functional
The following packages have something in common with the package functional. The packages are ordered in decreasing similarity.
- etl: Expandable token list operations
 - xargs: Define commands with many optional arguments
 - l3packages: High-level LaTeX3 concepts
 - l3backend: LaTeX3 backend drivers
 - zhlipsum: Chinese dummy text
 - l3experimental: Experimental LaTeX3 concepts
 - l3keys2e: LaTeX2ε option processing using LaTeX3 keys
 - xgalley: Control text feeding onto the page
 - expl3: Wrapper package for experimental LaTeX3
 - l3backend-dev: LaTeX3 backend drivers (dev)
 - xtemplate: A high-level interface for declaring document commands
 - xparse: A generic document command parser
 - erw-l3: Utilities based on LaTeX3
 - l3regex: Regular expression facilities for LaTeX
 - clistmap: Map and iterate over LaTeX3 clists
 - rescansync: Re-scan tokens with synctex information
 - lt3rawobjects: Objects and proxies in LaTeX3
 - lt3graph: Provide a graph datastructure for experimental LaTeX3
 - withargs: In-place argument substitution
 - keyparse: Key based parser
 - xpeekahead: A simple way for peeking ahead after commands and environments
 - cdcmd: Expandable conditional commands for LaTeX
 - enverb: Read an environment verbatim
 - xfp: Interface to the LaTeX3 floating point unit
 - unravel: Watching TeX digest tokens
 - fistrum: Access to 150 paragraphs of Lorem Fistrum very dummy text
 - cnltx: LaTeX tools and documenting facilities
 - lipsum: Easy access to the Lorem Ipsum and other dummy texts
 - kantlipsum: Generate sentences in Kant's style
 - switch: A constant time/expandable switch/case
 - pkginfograb: Collect LaTeX package infos in a regular way