Add a couple more simple language examples to the website

CONTRIBUTING.md

@@ -35,12 +35,6 @@ Run this command to build and test the main Rust codebase:
 cargo test
 ```
 
-Run this command to make a release build and install it on your `PATH`:
-
-```sh
-cargo install --locked --path crates/adroit
-```
-
 ## JavaScript
 
 We use Bun for our [website][] and for our VS Code extension. To work with the

packages/website/src/index.md

@@ -11,26 +11,34 @@ platform from the latest GitHub release:
 ### macOS Apple Silicon
 
 ```sh
-sudo curl -L https://github.com/adroit-lang/adroit/releases/download/v0.2.2/adroit-aarch64-apple-darwin -o /usr/local/bin/adroit && sudo chmod +x /usr/local/bin/adroit
+sudo curl -L https://github.com/adroit-lang/adroit/releases/download/v0.2.2/adroit-aarch64-apple-darwin -o /usr/local/bin/adroit
+sudo chmod +x /usr/local/bin/adroit
 ```
 
 ### macOS Intel
 
 ```sh
-sudo curl -L https://github.com/adroit-lang/adroit/releases/download/v0.2.2/adroit-x86_64-apple-darwin -o /usr/local/bin/adroit && sudo chmod +x /usr/local/bin/adroit
+sudo curl -L https://github.com/adroit-lang/adroit/releases/download/v0.2.2/adroit-x86_64-apple-darwin -o /usr/local/bin/adroit
+sudo chmod +x /usr/local/bin/adroit
 ```
 
 ### Linux x64
 
 ```sh
-sudo curl -L https://github.com/adroit-lang/adroit/releases/download/v0.2.2/adroit-x86_64-unknown-linux-musl -o /usr/local/bin/adroit && sudo chmod +x /usr/local/bin/adroit
+sudo curl -L https://github.com/adroit-lang/adroit/releases/download/v0.2.2/adroit-x86_64-unknown-linux-musl -o /usr/local/bin/adroit
+sudo chmod +x /usr/local/bin/adroit
 ```
 
 ### Building from source
 
 If none of those prebuilt binaries work for you, you can instead build Adroit
-from source by following the [`CONTRIBUTING.md`][] instructions in the GitHub
-repo.
+from source. First install [Git][] and [Rust][], then run these commands:
+
+```sh
+git clone --depth 1 --branch v0.2.2 https://github.com/adroit-lang/adroit.git
+cd adroit
+cargo install --locked --path crates/adroit
+```
 
 ## Editor support
 
@@ -50,9 +58,50 @@ adroit --help
 Currently Adroit is in the early stages of development and has no interpreter
 and no compiler backend, so there is no way to run an Adroit program.
 
+By convention, Adroit source file names end with the `.adroit` extension.
+
 ## Language
 
-Here is an example function implementing matrix multiplication in Adroit:
+Here is an Adroit function that takes a floating-point number as input, and
+returns the square of that number as output:
+
+```adroit
+def square(x: Float): Float = x * x
+```
+
+Within the body of a function, you can use `let` to give an intermediate value a
+name; then you write the return value of the function after all your
+`let`-bindings:
+
+```adroit
+def foo(x: Float, y: Float): Float =
+  let a = x + y
+  let b = x * y
+  a / b
+```
+
+Indentation is never significant in Adroit, but newlines are sometimes
+significant; as you can see above, you can end a `let`-binding with a newline,
+but if you'd prefer to put more on one line, you can instead use a semicolon:
+
+```adroit
+def tesseract(x: Float): Float = let y = x * x; y * y
+```
+
+Functions can be generic:
+
+```adroit
+def identity[T](x: T): T = x
+```
+
+Adroit currently has three standard library modules:
+
+- `"array"`
+- `"autodiff"`
+- `"math"`
+
+Here is an example using a couple functions from the `"array"` module to
+implement matrix multiplication:
 
 ```adroit
 import "array" use for, sum
@@ -65,5 +114,6 @@ def mmul[M, N, P](
     sum(for k => a[i, k] * b[k, j])
 ```
 
-[`CONTRIBUTING.md`]: https://github.com/adroit-lang/adroit/blob/main/CONTRIBUTING.md
 [from the VS Code Marketplace]: https://marketplace.visualstudio.com/items?itemName=adroit-lang.adroit-vscode
+[git]: https://git-scm.com/downloads
+[rust]: https://www.rust-lang.org/tools/install