Package management and reproducible environments

Julius Krumbiegel also has a great blog post with more details on Julia environments.

Julia packages can be configured (in a file called Project.toml) on a per-project basis. The packaged sources and compiled versions are stored in a central location, e.g. ~/.julia/packages and ~/.julia/compiled on Linux systems, but the configuration of packages to be used can be local to a project. The Pkg package is used to modify the local project’s configuration. (An alternative is “package mode” in the read-eval-print-loop or REPL, which we will show at the summer school.) Start julia in the directory of the cloned SMLP2024 repository

using Pkg        # there's a package called 'Pkg' to manipulate package configs
Pkg.activate(".")# activate the current directory as the project

If you’ve received an environment from someone/somewhere else – such as this course repository – then you’ll need to first “instantiate” it (i.e., install all the dependencies).

Pkg.instantiate()# only needed the first time you work in a project
Pkg.update()     # get the latest package versions compatible with the project

Pkg.status()

Occasionally the Pkg.status function call will give info about new versions being available but blocked by requirements of other packages. This is to be expected - the package system is large and the web of dependencies are complex. Generally the Julia package system is very good at resolving dependencies.