opam

About opam

From Debian's package description

OPAM stands for OCaml PAckage Manager. It aims to suit to a vast number of users and use cases, and has unique features:

• Powerful handling of dependencies: versions constraints, optional dependencies, conflicts, etc.
• Multiple repositories backends: HTTP, rsync, git
• Ease to create packages and repositories
• Ability to switch between different compiler versions

Typically, OPAM will probably make your life easier if you recognize yourself in at least one of these profiles:

• You use multiple versions of the OCaml compiler, or you hack the compiler yourself and needs to frequently switch between compiler versions.
• You use or develop software that needs a specific and/or modified version of the OCaml compiler to be installed.
• You use or develop software that depends on a specific version of an OCaml library, or you just want to install a specific version of a package, not just the latest one.
• You want to create your own packages yourself, put them on your own repository, with minimal effort.

From Debian's description of the opam package, under that package's license.