Mercurial and its near future

Mercurial is a distributed version control system, similar to Git but easier and for some aspect more powerfull. Version control systems should be used by all persons working with code, like scientists. Mercurial is particularly adapted for scientists.

We use Mercurial for most of the Fluiddyn packages (hosted on https://foss.heptapod.net/ , Heptapod being a Gitlab fork supporting Mercurial) and I use it on a daily basis to interact with Git projects hosted on Github and Gitlab. I also use Mercurial to teach version control to students and colleagues.

Mercurial is a Python application which works with extensions which are Python packages. With the hg-git extension ( https://foss.heptapod.net/mercurial/hg-git ), Mercurial can be used as a Git client, to interact with projects hosted on Github and Gitlab. I see that Mecurial is really nicer than the official Git client.

The Git client is at the same time too complex (with notions like staging area, blobs, trees, branches, HEAD, … and complicated commands) and not good regarding history edition (need of force push). With Mercurial simple things are simple and more advanced tasks (often related to history edition) are simple and safe.

Mercurial is still an active projects with professional developers working on its development. However, Mercurial, which is a Python application, did not follow Python improvements in terms of packaging. For example, Mercurial release manager does not yet upload wheels on pypi.org, so that pip install mercurial trigger local compilation. Moreover, the Rust extension is not compiled by default.

Tools like pipx , uv and conda-app should be perfect to install and manage Mercurial. One should be able to install and setup a good Mercurial environment with something like: 

uv tool install mercurial
echo 'eval "$(hg generate-shell-completion bash)"' >> ~/.bashrc
hg admin-extension --enable topic evolve absorb rebase hg-git
hg config --set ui.name "my_login <toto@univ-grenoble-alpes.fr>"
hg config --set ui.tweakdefaults True
hg config --set alias.lg "log -G"

I opened few issues about these needs: https://bz.mercurial-scm.org/show_bug.cgi?id=6923

I worked on a demonstrator that uses Github Actions to build Mercurial wheels.

I worked on conda-app so that students using miniforge can easily get a good Mercurial on all mainstream platforms (including Windows and macOS). 

conda activate base
pip install conda-app
conda-app install mercurial

I also invested some time on two merge requests on Mercurial main development repository https://foss.heptapod.net/mercurial/mercurial-devel/ :