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| <h1 id="static-guarantees"><a class="header" href="#static-guarantees">Static Guarantees</a></h1> |
| <p>Rust's type system prevents data races at compile time (see <a href="https://doc.rust-lang.org/core/marker/trait.Send.html"><code>Send</code></a> and |
| <a href="https://doc.rust-lang.org/core/marker/trait.Sync.html"><code>Sync</code></a> traits). The type system can also be used to check other properties at |
| compile time; reducing the need for runtime checks in some cases.</p> |
| <p>When applied to embedded programs these <em>static checks</em> can be used, for |
| example, to enforce that configuration of I/O interfaces is done properly. For |
| instance, one can design an API where it is only possible to initialize a serial |
| interface by first configuring the pins that will be used by the interface.</p> |
| <p>One can also statically check that operations, like setting a pin low, can only |
| be performed on correctly configured peripherals. For example, trying to change |
| the output state of a pin configured in floating input mode would raise a |
| compile error.</p> |
| <p>And, as seen in the previous chapter, the concept of ownership can be applied |
| to peripherals to ensure that only certain parts of a program can modify a |
| peripheral. This <em>access control</em> makes software easier to reason about |
| compared to the alternative of treating peripherals as global mutable state.</p> |
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