Add Noir/Rust syntax example section

noir_by_example/.gitignore

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+target
+Prover.toml
+Verifier.toml

noir_by_example/Cargo.toml

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+[workspace]
+members = [
+    "simple_macros/rust",
+    "loops/rust"
+]
+resolver = "1"

noir_by_example/Nargo.toml

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+[workspace]
+members = [
+    "simple_macros/noir",
+    "loops/noir"
+]

noir_by_example/README.md

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+# Examples showcasing syntax, libraries, and data structures
+
+These will show Noir side-by-side against [Rust by example](https://doc.rust-lang.org/rust-by-example/).
+
+The goal is to highlight the similarities and differences in the language and design patterns.
+
+## Tooling
+
+You will need:
+- `nargo` installed [via noirup](https://noir-lang.org/docs/getting_started/installation/)
+- `cargo` installed [via rustup](https://www.rust-lang.org/tools/install) (optional: to see Rust output)
+
+## What is not covered
+
+The surrounding build artifacts (and additional proving/verifying artifacts for Noir) are not explored in this example.
+
+# Usage
+
+The following commands can be run at the top level `noir_by_example`, or withing the specific topic directory.
+Eg: `cd simple_macros`
+
+## Compiling
+
+- `nargo compile`
+- `cargo build`
+
+## Running main
+
+- `nargo execute`
+- `cargo run` # topic-level only
+
+## Running tests
+
+Simply run:
+- `nargo test`
+- `cargo test`
+
+To see output from `println`:
+- `nargo test --show-output`
+- `cargo test -- --nocapture`
+
+To test specific functions, a substring of its name can be added to the end.
+Eg, `nargo test macro`, to run tests who's name contains the string `macro`.
+
+
+# Adding to this repository - GOOD FIRST ISSUES
+
+The Noir documentation has many good pages explaining the syntax with examples, similarly with Rust.
+
+For instance for macro function example:
+- Noir example in [(Quasi) Quote](https://noir-lang.org/docs/dev/noir/concepts/comptime#lowering)
+- Rust example in [macros](https://doc.rust-lang.org/rust-by-example/macros.html)
+
+Example functions can be added to [main.nr](./noir/src/main.nr) with a 1:1 corresponding [main.rs](./rust/src/main.rs) equivalent.
+
+# Adding to this repository
+
+To add a new section:
+- Go to the directory: `cd noir_by_example`
+- Use the script: `./new_topic.sh topic_name`
+- Then equivalent functionality to the `noir` and `rust` projects.

noir_by_example/loops/noir/Nargo.toml

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+[package]
+name = "loops"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.34.0"
+
+[dependencies]

noir_by_example/loops/noir/src/main.nr

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+fn fixed_loop() {
+    let len = 10;
+
+    // Loop from 1 to l (inclusive)
+    for i in 1..len + 1 {
+        print("Loop iteration: ");
+        println(i);
+    }
+}
+
+fn variable_loop(len: u32) {
+    let MAX_LEN = 20;
+    assert(len <= MAX_LEN);
+    // Loop from 1 to MAX_LEN
+    for i in 1..MAX_LEN as u32 + 1 {
+        // only print when beneath len (inclusive)
+        if (i <= len) {
+            print("Variable loop iteration: ");
+            println(i);
+        }
+    }
+}
+
+// Parameters read from Prover.toml file
+fn main(loop_length: u32) {
+    println("\nLOOPS START");
+    fixed_loop();
+    variable_loop(loop_length);
+    println("LOOPS END\n");
+}
+
+#[test]
+fn test_loops() {
+    main(5);
+}

noir_by_example/loops/rust/Cargo.toml

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+[package]
+name = "loops"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

noir_by_example/loops/rust/src/main.rs

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+// Need standard environment lib for command line arguments
+use std::env;
+
+fn fixed_loop() {
+    let l = 10;
+
+    // Loop from 1 to l (inclusive)
+    for i in 1..=l {
+        println!("Loop iteration: {}", i);
+    }
+}
+
+fn variable_loop(len: u32) {
+    // Loop from 1 to len (inclusive)
+    for i in 1..=len {
+        println!("Variable loop iteration: {}", i);
+    }
+}
+
+fn main() {
+    println!("\nLOOPS START");
+    const DEFAULT: u32 = 5;
+    // Read first command line argument
+    let args: Vec<String> = env::args().collect();
+    let loop_length = if args.len() > 1 {
+        args[1].parse().unwrap_or(DEFAULT)
+    } else {
+        DEFAULT // Default value if no argument is provided
+    };
+
+    fixed_loop();
+    variable_loop(loop_length); // variable
+    println!("\nLOOPS END");
+}
+
+#[test]
+fn test_loops() {
+    main();
+}

noir_by_example/new_topic.sh

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+#!/bin/bash
+echo "This command is for creating a subdirectory for a new topic."
+
+# Only run from location of script
+script_dir="$(cd "$(dirname "$0")" && pwd)"
+current_dir="$(pwd)"
+
+if [ "$script_dir" != "$current_dir" ]; then
+    echo "Error: Script intended to be run from its directory (noir_by_example)"
+    exit 1
+fi
+
+if [ $# -eq 0 ]; then
+    echo "Error: Please provide a topic_name as an argument."
+    exit 1
+fi
+
+# Create topic dir from command line argument
+dir_name="$1"
+mkdir -p "$dir_name"
+
+if [ $? -eq 0 ]; then
+    echo "Directory '$dir_name' created (or already exists)."
+    cd "$dir_name"
+
+    echo "Creating Noir project..."
+    nargo new noir
+    if [ $? -ne 0 ]; then
+        echo "Error: Failed to create new Noir project."
+        exit 1
+    fi
+
+    echo "Creating Rust ..."
+    cargo new rust
+    if [ $? -ne 0 ]; then
+        echo "Error: Failed to create new Rust project."
+        exit 1
+    fi
+
+else
+    echo "Error: Failed to create directory '$dir_name'."
+    exit 1
+fi
+
+cd ..

noir_by_example/simple_macros/noir/Nargo.toml

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+[package]
+name = "simple_macros"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.34.0"
+
+[dependencies]

noir_by_example/simple_macros/noir/src/main.nr

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+// https://noir-lang.org/docs/dev/noir/concepts/comptime#lowering
+// a compile-time function that returns a `Quoted` type
+comptime fn say_hello() -> Quoted {
+    quote {
+        // the macro will expand into the contents of this quote
+        // this single quote isn't divided to take arguments
+        println("Hello!")
+    }
+}
+
+fn main() {
+    println("\nSIMPLE_MACRO START");
+    // This call will unquote into `println!("Hello!")`
+    let res = say_hello!();
+    println("SIMPLE_MACRO END\n");
+    res
+}
+
+#[test]
+fn test_macros() {
+    main()
+}

noir_by_example/simple_macros/rust/Cargo.toml

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+[package]
+name = "simple_macros"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

noir_by_example/simple_macros/rust/src/main.rs

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+// https://doc.rust-lang.org/rust-by-example/macros.html
+// This is a simple macro named `say_hello`.
+macro_rules! say_hello {
+    // `()` indicates that the macro takes no argument.
+    () => {
+        // The macro will expand into the contents of this block.
+        println!("Hello!")
+    };
+}
+
+fn main() {
+    println!("\nSIMPLE_MACRO START");
+    // This call will expand into `println!("Hello!")`
+    let res = say_hello!();
+    println!("SIMPLE_MACRO END\n");
+    res
+}
+
+#[test]
+fn test_macros() {
+    main()
+}