Cabal documentation

Where to read it

These docs will be built and deployed whenever a release is made, and can be read at: https://www.haskell.org/cabal/users-guide/

In addition, the docs are taken directly from git and hosted at: http://cabal.readthedocs.io/

How to build it

Building the documentation requires Python 3 and PIP. Run the following command either from the root of the cabal repository or from the docs/ subdirectory:

make users-guide

Note: Python on Mac OS X dislikes LC_CTYPE=UTF-8, so unset the variable and instead set LC_ALL=en_US.UTF-8.

How to update dependencies

Once in a while you need to update Python dependencies (for instance, when Dependabot alerts about possible security flaw). The list of transitive dependencies (requirements.txt) is generated from the list of direct dependencies in requirements.in. To perform the generation step run

> make users-guide-requirements

either from the root of the cabal repository or from the docs/ subdirectory.

Note that generating requirements.txt is sensitive to the Python version. The version currently used is stamped at the top of requirements.txt. Normally, we would expect the same version of Python to be used for regeneration. An easy way to enforce a particular version is to perform regeneration in a Docker container, e.g. (from the root of repository):

> docker run -itv $PWD:/cabal python:3.10-alpine sh
...
# apk add make
...
# cd cabal
# make users-guide-requirements

One way to make sure the dependencies are reasonably up to date is to remove requirements.txt and regenerate it as described above. But in some cases you may have to add a bound manually to requirements.in, e.g. requests >= 2.31.0.

Gitpod workflow

From a fork of cabal, these docs can be edited online with gitpod:

• Open in gitpod https://gitpod.io/#https://github.com/username/cabal
• Install the virtual environment prerequisite. > sudo apt install python3.8-venv
• Build the user guide > make users-guide.
• Open the guide in a local browser. > python -m http.server 8000 --directory=dist-newstyle/doc/users-guide

Make your edits, rebuild the guide and refresh the browser to preview the changes. When happy, commit your changes with git in the included terminal.

Caveats, for newcomers to RST from MD

RST does not allow you to skip section levels when nesting, like MD does. So, you cannot have

    Section heading
    ===============

    Some unimportant block
    """"""""""""""""""""""

instead you need to observe order and either promote your block:

    Section heading
    ===============

    Some not quite so important block
    ---------------------------------

or introduce more subsections:

    Section heading
    ===============

    Subsection
    ----------

    Subsubsection
    ^^^^^^^^^^^^^

    Some unimportant block
    """"""""""""""""""""""

• RST simply parses a file and interprets headings to indicate the start of a new block,

  • at the level implied by the header's adornment, if the adornment was previously encountered in this file,
  • at one level deeper than the previous block, otherwise.

  This means that a lot of confusion can arise when people use different adornments to signify the same depth in different files.

  To eliminate this confusion, please stick to the adornment order recommended by the Sphinx team:

    ####
    Part
    ####

    *******
    Chapter
    *******

    Section
    =======

    Subsection
    ----------

    Subsubsection
    ^^^^^^^^^^^^^

    Paragraph
    """""""""

• The Read-The-Docs stylesheet does not support multiple top-level sections in a file that is linked to from the top-most TOC (in index.rst). It will mess up the sidebar. E.g. you cannot link to a cabal.rst with sections "Introduction", "Using Cabal", "Epilogue" from index.rst.

  One solution is to have a single section, e.g. "All About Cabal", in cabal.rst and make the other blocks subsections of that.

  Another solution is to link via an indirection, e.g. create all-about-cabal.rst, where you include cabal.rst using the .. toctree:: command and then link to all-about-cabal.rst from index.rst. This will effectively "push down" all blocks by one layer and solve the problem without having to change cabal.rst.

• We use extlinks to shorten links to commonly referred resources (wiki, issue trackers).

  E.g. you can use the more convenient short syntax

    :issue:`123`
  

  which is expanded into a hyperlink

    `#123 <https://github.com/haskell/cabal/issues/123>`__
  

  See conf.py for list of currently defined link shorteners.