lean4-htt/doc/dev/mdbook.md
2023-09-20 15:13:27 -07:00

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# Documentation
The Lean `doc` folder contains the [Lean Manual](https://lean-lang.org/lean4/doc/) and is
authored in a combination of markdown (`*.md`) files and literate Lean files. The .lean files are
preprocessed using a tool called [LeanInk](https://github.com/leanprover/leanink) and
[Alectryon](https://github.com/Kha/alectryon) which produces a generated markdown file. We then run
`mdbook` on the result to generate the html pages.
## Settings
We are using the following settings while editing the markdown docs.
```json
{
"files.insertFinalNewline": true,
"files.trimTrailingWhitespace": true,
"[markdown]": {
"rewrap.wrappingColumn": 70
}
}
```
## Build
### Using Nix
Building the manual using Nix (which is what the CI does) is as easy as
```bash
$ nix build --update-input lean ./doc
```
You can also open a shell with `mdbook` for running the commands mentioned below with
`nix develop ./doc#book`. Otherwise, read on.
### Manually
To build and test the book you have to preprocess the .lean files with Alectryon then use our own
fork of the Rust tool named [mdbook](https://github.com/leanprover/mdbook). We have our own fork of
mdBook with the following additional features:
* Add support for hiding lines in other languages
[#1339](https://github.com/rust-lang/mdBook/pull/1339)
* Make `mdbook test` call the `lean` compiler to test the snippets.
* Ability to test a single chapter at a time which is handy when you
are working on that chapter. See the `--chapter` option.
So you need to setup these tools before you can run `mdBook`.
1. install [Rust](https://www.rust-lang.org/tools/install)
which provides you with the `cargo` tool for building rust packages.
Then run the following:
```bash
cargo install --git https://github.com/leanprover/mdBook mdbook
```
1. Clone https://github.com/leanprover/LeanInk.git and run `lake build` then make the resulting
binary available to Alectryon using e.g.
```bash
# make `leanInk` available in the current shell
export PATH=$PWD/build/bin:$PATH
```
1. Create a Python 3.10 environment.
1. Install Alectryon:
```
python3 -m pip install git+https://github.com/Kha/alectryon.git@typeid
```
1. Now you are ready to process the `*.lean` files using Alectryon as follows:
```
cd lean4/doc
alectryon --frontend lean4+markup examples/palindromes.lean --backend webpage -o palindromes.lean.md
```
Repeat this for the other .lean files you care about or write a script to process them all.
1. Now you can build the book using:
```
cd lean4/doc
mdbook build
```
This will put the HTML in a `out` folder so you can load `out/index.html` in your web browser and
it should look like https://lean-lang.org/lean4/doc/.
1. It is also handy to use e.g. [`mdbook watch`](https://rust-lang.github.io/mdBook/cli/watch.html)
in the `doc/` folder so that it keeps the html up to date while you are editing.
```bash
mdbook watch --open # opens the output in `out/` in your default browser
```
## Testing Lean Snippets
You can run the following in the `doc/` folder to test all the lean code snippets.
```bash
mdbook test
```
and you can use the `--chapter` option to test a specific chapter that you are working on:
```bash
mdbook test --chapter Array
```
Use chapter name `?` to get a list of all the chapter names.