All documentation is in English, but no particular dialect is preferred.

The documentation should be accessible to multiple audiences: both seasoned Rustaceans and relative newcomers, those with experience in statistical modelling or cryptography, as well as those new to the subjects. Since it is often impossible to write appropriate one-size-fits-all documentation, we prefer concise technical documentation with reference to extended articles aimed at more specific audiences.

API documentation

Rand crates

It is recommended to use nightly Rust for correct link handling.

To build all API documentation for all crates in the rust-random/rand repository, run:

# Build doc for all modules:
cargo doc --all --no-deps

# And open it:
xdg-open target/doc/rand/index.html

On Linux, it is easy to set up automatic rebuilds after any edit:

while inotifywait -r -e close_write src/ rand_*/; do cargo doc; done

After editing API documentation, we recommend testing examples:

cargo test --doc

Rand API docs are automatically built and hosted at for the latest code in master.

Getrandom crate

The rust-random/getrandom repository contains only a single crate, hence a simple cargo doc will suffice.

Cross-crate links

When referring to another crate, we prefer linking to the crate page on since (a) this includes the README documenting the purpose of the crate and (b) this links directly to both the repository and the API documentation. Example:

fn main() {
// Link to the crate page:
//! [`rand_chacha`]:

When referring to an item from within another crate,

  1. if that item is accessible via a crate dependency (even if not via the public API), use the Rust item path
  2. when linking to another crate within the rust-random/rand repository, relative paths within the generated documentation files (under target/doc) can be used; these work on but not currently on (see docs#204)
  3. if neither of the above are applicable, use an absolute link
  4. consider revising documentation, e.g. refer to the crate instead


// We depend on rand_core, therefore can use the Rust path:
/// [`BlockRngCore`]: rand_core::block::BlockRngCore

// rand_chacha is not a dependency, but is within the same repository:
//! [`ChaCha20Rng`]: ../../rand_chacha/struct.ChaCha20Rng.html

// Link directly to, with major & minor but no patch version:

Auxiliary documentation

README files

README files contain a brief introduction to the crate, shield badges, useful links, feature-flag documentation, licence information, and potentially an example.

For the most part these files do not have any continuous testing. Where examples are included (currently only for the rand_jitter crate), we enable continuous testing via doc_comment (see onwards).


Changelog formats are based on the Keep a Changelog format.

All significant changes merged since the last release should be listed under an [Unreleased] section at the top of log.

The book

The source to this book is contained in the rust-random/book repository. It is built using mdbook, which makes building and testing easy:

cargo install mdbook --version "^0.2"

mdbook build --open
mdbook test

# To automatically rebuild after any changes:
mdbook watch

Note that links in the book are relative and designed to work in the published book. If you build the book locally, you might want to set up a symbolic link pointing to your build of the API documentation:

ln -s ../rand/target/doc rand