Composer vs Spack

Composer manages dependencies for PHP projects, installing and updating the libraries each project declares. By default, it keeps those dependencies in a directory within the project, and it can also manage a global project. It resolves dependencies and supports lockfiles, workspaces, private registry authentication, and offline installation. Packagist is its default package source; custom Composer, version-control, and local-path repositories are also supported. Composer integrates with Fossil, Git, Mercurial, Perforce, and Subversion. It can be installed locally or as a system-wide executable on Windows, Linux, and macOS. The latest version requires PHP 7.2.5 or later; the 2.2.x LTS line supports PHP 5.3.2 and later. Its audit command checks installed packages for security advisories, abandoned packages, malware flags, and other dependency policies. Composer is free under the MIT license. Plugins and scripts can run with the user's permissions, so the project advises against running Composer as root with untrusted packages.

Spack is a package manager for installing scientific software on supercomputers, Linux, macOS, and Windows. It is designed for large supercomputing centers that share software across clusters and varied architectures, and is available at free. Users can choose package versions, compiler choices, target architectures, and compile-time options, while controlling direct and transitive dependencies. Spack can build stacks that combine Python or R packages with C, C++, or Fortran libraries. Each distinct package and dependency configuration receives its own prefix, so different builds can coexist without a new installation disrupting an existing one. Software can be installed to a user-selected directory without administrator privileges. Spack primarily builds customized software from source and also supports binary installation through build caches. It supports lockfiles, environment management, and private registries. Package recipes are Python scripts, and the `spack create` command generates starter boilerplate. The project is distributed under either the MIT license or Apache License 2.0, at the user's option.