rust: add README.md

Author: jwatson0

runtime/rust/README.md

@@ -0,0 +1,114 @@
+## Rust
+
+### Versions
+
+-   New versions every ~6 weeks
+-   1.91.1 released 2025-11-10
+-   1.91 released 2025-10-30
+-   1.89.0 released 2025-08-07
+-   Rust Editions - Rust uses editions to make backwards-incompatible changes. Editions are a mechanism for opt-in changes that may otherwise pose a backwards compatibility risk.
+-   New Editions every ~3 years
+-   Rust 2015, the default edition from Rust 1.0.
+-   Rust 2018, which added path and module system changes and was released alongside 1.31 in December 2018.
+-   Rust 2021, released alongside 1.56 in October 2021.
+-   Rust 2024, released alongside 1.85 in February 2025.
+
+### Considerations
+
+1.  "Engineers cited performance, lack of a garbage collector, safety, and pleasantness of working in the language as reasons for the adoption."
+
+2.  "Hoare has described Rust as targeted at frustrated C++ developers."
+
+3.  "Stability as a Deliverable" <https://blog.rust-lang.org/2014/10/30/Stability/>
+
+4.  Helpful errors:
+
+```
+    error[E0599]: no method named \`to<sub>str</sub>\` found for enum
+    56 | assert<sub>eq</sub>!(msg.to<sub>str</sub>().unwrap(), "foo");
+    help: there is a method \`to<sub>string</sub>\` with a similar name
+```
+
+5.  rustdoc generates docs from source <https://doc.rust-lang.org/rustdoc/>
+
+### Tips
+
+1.  Env settings
+
+```
+    CARGO_TERM_COLOR: always
+```
+
+2.  Debian install
+
+```
+    apt install rustup
+    rustup default stable
+```
+
+### Basic build/test loop
+
+```
+    cargo build
+    cargo test
+    cargo clean
+    cargo build --locked --release --all-targets
+```
+
+### Third-party packages
+
+1.  Cargo (crates.io)
+
+    <https://crates.io/>
+
+    1.  Adding to project
+
+        Cargo.toml:
+
+```
+        [package]
+        name = "hello-world"
+        version = "0.1.0"
+        edition = "2021"
+
+        [dependencies]
+        regex = "1.0"
+```
+
+### Native Interoperability
+
+<https://docs.rust-embedded.org/book/interoperability/c-with-rust.html>
+
+-   C headers, externs, static link with LLVM
+-   There is a tool called bindgen which will generate Rust interfaces to C libs
+-   Shared lib loading: <https://docs.rs/libloading/latest/libloading/> For shared libs written in Rust or another language
+-   Working with dynamically loaded libraries often involves using the unsafe keyword
+
+### Websockets example
+
+<https://lib.rs/crates/tungstenite>
+
+```
+use tungstenite::{connect, Message};
+let (mut socket, _response) =
+    connect("ws://corefx-net-http11.azurewebsites.net/WebSocket/EchoWebSocket.ashx")
+        .expect("Can't connect");
+socket
+    .send(Message::Text("Hello WebSocket".into()))
+    .unwrap();
+let msg = socket.read().expect("Error reading message");
+```
+
+### Cross-platform compile from linux
+
+```
+    rustup target list
+    cargo build --target x86_64-unknown-linux-gnu
+    cargo build --target x86_64-apple-darwin
+    cargo build --target x86_64-pc-windows-msvc
+```
+
+### Introspection
+
+Not built in, but possible with macros
+