[er7-redact](../index.md) → examples
# Examples
Runnable programs demonstrating the `er7-redact` crate. Each is a single
file with no setup, invoked via `cargo run --example <name>`.
| [redact_a_message](redact_a_message.rs) | The built-in policy end to end: what goes, what stays, and why the message still works. |
| [write_a_policy](write_a_policy.rs) | Three ways to say what to redact — in Rust, from a file, or by extending a built-in. |
| [reject_by_default](reject_by_default.rs) | The other posture: reject every value, with `keep` rules accepting what a test needs. |
| [pseudonyms_and_linkage](pseudonyms_and_linkage.rs) | Why an identifier becomes a pseudonym rather than a blank, what that buys, and what it costs. |
| [read_the_report](read_the_report.rs) | The audit trail: one row per position changed, and no values in it. |
| [redact_absent_empty_null](redact_absent_empty_null.rs) | The three states HL7 keeps apart, and why redaction leaves two of them alone. |
## Running
```sh
# Build them all without running — this is what `cargo test` and
# `cargo clippy --all-targets` do, so a broken example fails the build.
cargo build --examples
# Run one.
cargo run --example redact_a_message
# Run them all.
for e in redact_a_message write_a_policy reject_by_default \
pseudonyms_and_linkage read_the_report redact_absent_empty_null; do
echo "== $e"; cargo run --quiet --example "$e";
done
```
## Suggested order
If you are new to the crate, read them in this order — each builds on the
one before:
1. **redact_a_message** — what redaction does, and what it leaves.
2. **write_a_policy** — how to say what you want redacted.
3. **read_the_report** — how to check what actually happened.
4. **redact_absent_empty_null** — the distinction that matters most clinically.
5. **pseudonyms_and_linkage** — how to keep a message joinable, and the
price of doing so.
6. **reject_by_default** — what to do when you do not trust the list.
## Guarantees
- Every example uses only the **published public API** — no `pub(crate)`
items, no internals. If an example needs something the library does not
export, the library is missing it.
- Every example **asserts its own results**, so a clean exit means it
passed. They are compiled by `cargo test` and linted by
`cargo clippy --all-targets`, so a tutorial that stopped being true
fails the build.
- Every message is **synthetic**. Names are obviously fictional
(`EVERYWOMAN^EVE`, `JONES^WILLIAM`) and identifiers obviously fake
(`PATID1234`, `444333222`). No example contains, or could collide with,
real patient data — see [`AGENTS/safety.md`](../AGENTS/safety.md), which
matters more in this repository than in any of its siblings.
## See also
- [`docs/usage/`](../docs/usage/index.md) — the same ground as prose, with
more explanation
- [`docs/policies/`](../docs/policies/index.md) — the policy file format
and the built-in tables
- [`docs/api/`](../docs/api/index.md) — the complete public API surface
- [`spec/`](../spec/index.md) — the normative rules these examples
illustrate
- [`samples/`](../samples/) — the ER7 messages and the policy file the CLI
examples use