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The domain hosts online documentation for the Stack project, using Read the Docs with MkDocs and the Material for MkDocs theme.

Read the Docs

The Read the Docs project is named 'The Haskell Tool Stack'.

The set up on the Read the Docs web site involves two page redirects when there are HTTP 404 Not Found errors:

/ -> /README/
/README/ -> /

The 'Home' MkDocs page is doc/

The / -> /README/ redirect ensures that (for example) will, if not found, redirect to

The /README/ -> / redirect ensures that (for example) will, if not found, redirect to

MkDocs rendering of differed before and after MkDocs 1.0. Prior to MkDocs 1.0, rendered to /README/index.html. From MkDocs 1.0, rendered to /index.html. The two redirects above ensure that the Read the Docs flyout works when moving between different versions of the home page using the flyout.

Stack moved from MkDocs 0.17.3 to MkDocs 1.3.1 after publishing the documentation for Stack 2.7.5.

A YAML configuration file, .readthedocs.yaml is included in the repository root directory. See It specifies a Python requirements file in doc/requirements.txt.


The doc/requirements.txt file pins the version of MkDocs. As at 2 September 2021 it is set to:


A YAML configuration file, mkdocs.yml is included in the repository root directory. See

site_dir: _site specifies the directory where the output HTML and other files are created. This directory is added to the .gitignore file.

MkDocs 1.3.0 replaced the pages: key with the nav: key.

Material for MkDocs

Stack moved from the default readthedocs theme to Material for MkDocs after publishing the documentation for Stack 2.7.5. The new theme has extensive online documentation and features that the default theme lacked.

The Material for MkDocs theme is loaded in the doc/requirements.txt file:


The theme is specified in the mkdocs.yml file:

  name: material
    primary: 'deep purple'
    accent: 'deep purple'
    logo: material/language-haskell

Read the Docs requires JQuery for its JavaScript code to inject the flyout menu. Material for MkDocs does not come with JQuery. So, the following is required in the mkdocs.yml file:

- ''

The Read the Docs flyout is formatted with a font-size that is 90% of the body font-size. Material for MkDocs has a body font-size that is 0.5rem, which is small. A little additional CSS is added to the extra.css file, to force the final font-size to be 0.7rem. That size is consistent with that of other elements in the theme.

body {
    font-size: 0.777778rem;

Material for MkDocs default suggestions for syntax highlighting in code blocks are applied. They are specified in the mkdocs.yml file as:

- pymdownx.highlight:
    anchor_linenums: true
- pymdownx.inlinehilite
- pymdownx.snippets
- pymdownx.superfences

Other extensions to the basic Markdown syntax used include:

  • Admonitions


    This is an example of an 'info' admonition.

  • Content tabs, which can be nested


    Content tabs are used so that users of different operating systems, or different distributions of Linux, can be presented with content specific to their needs.

  • icons and emojis


    The octicons-tag-24 icon () is used to refer to versions of Stack. The material-cloud-download-outline icon () is used to signify a download link.


Online documentation can be tested by establishing a branch on the repository that is then configured on the Read the Docs web site as 'Active' but 'Hidden' - for example branch mkdocs-test. As the branch is 'Hidden' it does not appear in the Read the Docs flyout or search results.