– In typical package management systems such as apt or Homebrew, only one version of a specific package name can be installed throughout the system. For this reason, the version is sometimes specified in the package name. (For example, distributing python3.9 and python3.10 as separate packages, etc.)
– Particularly problematic when multiple packages depend on one common package. Upgrading a library like OpenSSL will affect all packages that depend directly or indirectly on OpenSSL.
– Although the versions of compatible dependencies are loosely defined for each package, in some cases, there is a possibility that behavior may not be the same as before. Also, if the version you are trying to upgrade conflicts with the version required by a certain package, the upgrade may not be possible at all.
– In Nix, dependencies are defined as exact versions and specific builds, such as yc41q33h5xrw1zbyw5hp1y1ga0jk9hwd-openssl-1.1.1k. Therefore, dependency versions can be selected independently for each package. Because packages do not affect each other, you can safely install and upgrade packages. Additionally, with dependency pinning, the package is more likely to work as intended by the author.