Where’s Michael Torpey?

• It’s still me
• I got married in 2021 and took my wife’s name

Before 2018

• No package manager
• Install new packages by hand
  • download, extract, autoconf, configure, make
• Same process for each dependency
• Monolithic package distribution with GAP

GAP Days Fall 2018

• University of Siegen, 17–21 September 2018
• Among “further topics”: Package manager for GAP

Early prototype

• I hacked something together!
• End of week: PackageManager 0.1

Design philosophy

• Get something working quickly
• Reuse existing infrastructure
  • Build script
  • Package list
  • Checking packages
• Allow multiple sources
  • Package name (look up in official list)
  • Archive URL
  • Version control repo
• Do checks, and fail loudly

Used from inside GAP

gap> LoadPackage("automata");
#I  automata package is not available. Check that the name is correct
#I  and it is present in one of the GAP root directories (see '??RootPaths')
fail
gap> InstallPackage("automata");
#I  Getting PackageInfo URLs...
#I  Retrieving PackageInfo.g from https://gap-packages.github.io/automata/PackageInfo.g ...
#I  Downloading archive from URL https://github.com/gap-packages/automata/releases/download/v1.15/automata-1.15.tar.gz ...
#I  Saved archive to /tmp/gaptempdirc2LzuR/automata-1.15.tar.gz.pkgman
#I  Extracting to /home/mtorpey/.gap/pkg/automata-1.15 ...
true
gap> LoadPackage("automata");
─────────────────────────────────────────────────────────────────────────────────────────────────
Loading Automata 1.15 (Automata, a GAP package for finite state automata)
by Manuel Delgado (https://cmup.fc.up.pt/cmup/mdelgado/),
   Steve Linton (http://www-groups.dcs.st-and.ac.uk/~sal/), and
   José João Morais.
maintained by:
   Manuel Delgado (https://cmup.fc.up.pt/cmup/mdelgado/) and
   Steve Linton (http://www-groups.dcs.st-and.ac.uk/~sal/).
Homepage: https://gap-packages.github.io/automata/
Report issues at https://github.com/gap-packages/automata/issues
─────────────────────────────────────────────────────────────────────────────────────────────────
true
gap> 

User level only

• Only modifies ~/.gap/pkg/
• Doesn’t touch GAP install directory
• Doesn’t touch packages bundled with GAP

Bootstrapping packages

• GAP requires GAPDoc, primgrp, SmallGrp, and transgrp to run
• We now have InstallRequiredPackages
• Can load GAP with gap --bare
• In principle, only need to install PackageManager manually

Release timeline

Current state

• Included with GAP since 2019
• Definitely used by scripts
• Apparently used by people
• Co-authored by “The GAP Team”
• Often works correctly

Immediate things to work on

Things we don’t have

• Old versions of packages
• Auto-removing dependencies
• Updating GAP itself
• Caching?
• …

Bigger future plans

• Question: should the foundation of the package manager change?
• What was easy in 2018 might not be what’s best in 2025

Sources of packages

• URLs come from package list at https://github.com/gap-system/PackageDistro
• Submitted by package authors
• Most hosted at github.io (some under gap-packages organisation)
• Others at colostate.edu, rwth-aachen.de, tu-bs.de, uni-bielefeld.de
• Pros and cons

Model 1: Debian

• Tightly controlled package distribution
• Single source by default
• Debian authors test everything and only import new versions when they pass
• A bit like the monolithic distribution that comes with GAP
• Stable and Testing branches?

Model 2: PyPI/npm

• Wild West!
• Anyone can submit anything, only a few automated checks
• Still all stored in a single repository

Model 3: Status quo+

• Current system with some improvements
• List of package URLs would include older versions
  • Allows older packages to be installed
• Host structured data including dependency tree
  • Seriously reduces number of requests
  • Easy to cache/update locally?
• Mark packages as manually/automatically installed

Model 4: Do nothing

• No major structural change needed
• Focus on bug fixes and usability

Keep in touch

• How to use: https://gap-packages.github.io/PackageManager/
• Suggestions: https://github.com/gap-packages/PackageManager/issues
• Contributions: https://github.com/gap-packages/PackageManager/pulls
• Talk to me after!