10 files changed, 259 insertions, 0 deletions
diff --git a/users/wpcarro/scratch/rust/.gitignore b/users/wpcarro/scratch/rust/.gitignore
new file mode 100644
index 000000000000..9f970225adb6
--- /dev/null
+++ b/users/wpcarro/scratch/rust/.gitignore
@@ -0,0 +1 @@
+target/
\ No newline at end of file
diff --git a/users/wpcarro/scratch/rust/Cargo.lock b/users/wpcarro/scratch/rust/Cargo.lock
new file mode 100644
index 000000000000..28aa1250cea4
--- /dev/null
+++ b/users/wpcarro/scratch/rust/Cargo.lock
@@ -0,0 +1,89 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "itoa"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "112c678d4050afce233f4f2852bb2eb519230b3cf12f33585275537d7e41578d"
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.43"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0a2ca2c61bc9f3d74d2886294ab7b9853abd9c1ad903a3ac7815c58989bb7bab"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbe448f377a7d6961e30f5955f9b8d106c3f5e449d493ee1b125c1d43c2b5179"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "rust"
+version = "0.1.0"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
+[[package]]
+name = "ryu"
+version = "1.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3f6f92acf49d1b98f7a81226834412ada05458b7364277387724a237f062695"
+
+[[package]]
+name = "serde"
+version = "1.0.137"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "61ea8d54c77f8315140a05f4c7237403bf38b72704d031543aa1d16abbf517d1"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.137"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1f26faba0c3959972377d3b2d306ee9f71faee9714294e41bb777f83f88578be"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "serde_json"
+version = "1.0.81"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b7ce2b32a1aed03c558dc61a5cd328f15aff2dbc17daad8fb8af04d2100e15c"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.99"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "58dbef6ec655055e20b86b15a8cc6d439cca19b667537ac6a1369572d151ab13"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4f5b37a154999a8f3f98cc23a628d850e154479cd94decf3414696e12e31aaf"
diff --git a/users/wpcarro/scratch/rust/Cargo.toml b/users/wpcarro/scratch/rust/Cargo.toml
new file mode 100644
index 000000000000..76235d11d37d
--- /dev/null
+++ b/users/wpcarro/scratch/rust/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "rust"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+serde_json = "1.0.81"
+serde = { version = "1.0.137", features = ["derive"] }
diff --git a/users/wpcarro/scratch/rust/README.md b/users/wpcarro/scratch/rust/README.md
new file mode 100644
index 000000000000..9ff7dd97eaf6
--- /dev/null
+++ b/users/wpcarro/scratch/rust/README.md
@@ -0,0 +1,11 @@
+# Rust
+
+Watch me fumble around as I learn Rust.
+
+## Usage
+
+```shell
+$ nix-shell /depot -A users.wpcarro.scratch.rust
+$ cargo new json && cd ./json
+$ cargo run json
+```
diff --git a/users/wpcarro/scratch/rust/shell.nix b/users/wpcarro/scratch/rust/shell.nix
new file mode 100644
index 000000000000..98e2dbf4b29b
--- /dev/null
+++ b/users/wpcarro/scratch/rust/shell.nix
@@ -0,0 +1,7 @@
+{ pkgs ? import <nixpkgs> { }, ... }:
+
+pkgs.mkShell {
+  buildInputs = [
+    pkgs.cargo
+  ];
+}
diff --git a/users/wpcarro/scratch/rust/src/display/mod.rs b/users/wpcarro/scratch/rust/src/display/mod.rs
new file mode 100644
index 000000000000..838463109190
--- /dev/null
+++ b/users/wpcarro/scratch/rust/src/display/mod.rs
@@ -0,0 +1,13 @@
+use std::fmt;
+
+pub struct Person {
+    pub fname: String,
+    pub lname: String,
+    pub age: i8,
+}
+
+impl fmt::Display for Person {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}, {} ({} years old)", self.lname, self.fname, self.age)
+    }
+}
diff --git a/users/wpcarro/scratch/rust/src/json/mod.rs b/users/wpcarro/scratch/rust/src/json/mod.rs
new file mode 100644
index 000000000000..d3307b394ea4
--- /dev/null
+++ b/users/wpcarro/scratch/rust/src/json/mod.rs
@@ -0,0 +1,81 @@
+use serde::{Deserialize, Serialize};
+use serde_json::{json, Value};
+
+// From the serde_json docs:
+//
+// > There are three common ways that you might find yourself needing to work
+// > with JSON data in Rust.
+// >
+// > 1. As text data. An unprocessed string of JSON data that you receive on an
+// >    HTTP endpoint, read from a file, or prepare to send to a remote server.
+// > 2. As an untyped or loosely typed representation. Maybe you want to check
+// >    that some JSON data is valid before passing it on, but without knowing
+// >    the structure of what it contains. Or you want to do very basic
+// >    manipulations like insert a key in a particular spot.
+// > 3. As a strongly typed Rust data structure. When you expect all or most of
+// >    your data to conform to a particular structure and want to get real work
+// >    done without JSON’s loosey-goosey nature tripping you up.
+//
+// So let's take a look at all three...
+
+////////////////////////////////////////////////////////////////////////////////
+// Types
+////////////////////////////////////////////////////////////////////////////////
+
+#[derive(Serialize, Deserialize, Debug)]
+struct Person {
+    fname: String,
+    lname: String,
+    age: u8,
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Functions
+////////////////////////////////////////////////////////////////////////////////
+
+// 1) Reading/writing from/to plain text.
+//    TL;DR:
+//    - read:  serde_json::from_str(data)
+//    - write: x.to_string()
+pub fn one() {
+    let data = json!({
+        "fname": "William",
+        "lname": "Carroll",
+        "age": 30,
+    })
+    .to_string();
+
+    println!("result: {:?}", data);
+}
+
+// 2) Parse into a loosely typed representation; mutate it; serialize it back.
+//    TL;DR:
+//    - read:  serde_json::from_str(data)
+//    - write: x.to_string()
+pub fn two() {
+    let data = r#"{"fname":"William","lname":"Carroll","age":30}"#;
+
+    let mut parsed: Value = serde_json::from_str(data).unwrap();
+    parsed["fname"] = json!("Norm");
+    parsed["lname"] = json!("Macdonald");
+    parsed["age"] = json!(61);
+
+    let result = parsed.to_string();
+    println!("result: {:?}", result);
+}
+
+// 3) Parse into a strongly typed structure.
+//    TL;DR:
+//    - read:  serde_json::from_str(data)
+//    - write: serde_json::to_string(x).unwrap()
+pub fn three() {
+    let data = r#"{"fname":"William","lname":"Carroll","age":30}"#;
+
+    let mut read: Person = serde_json::from_str(data).unwrap();
+    read.fname = "Norm".to_string();
+    read.lname = "Macdonald".to_string();
+    read.age = 61;
+
+    let write = serde_json::to_string(&read).unwrap();
+    println!("result: {:?}", write);
+}
diff --git a/users/wpcarro/scratch/rust/src/main.rs b/users/wpcarro/scratch/rust/src/main.rs
new file mode 100644
index 000000000000..671b33093050
--- /dev/null
+++ b/users/wpcarro/scratch/rust/src/main.rs
@@ -0,0 +1,15 @@
+use serde::{Deserialize, Serialize};
+use serde_json::{json, Value};
+
+mod display;
+mod json;
+mod rc;
+mod stdin;
+
+////////////////////////////////////////////////////////////////////////////////
+// Main
+////////////////////////////////////////////////////////////////////////////////
+
+fn main() {
+    rc::example();
+}
diff --git a/users/wpcarro/scratch/rust/src/rc/mod.rs b/users/wpcarro/scratch/rust/src/rc/mod.rs
new file mode 100644
index 000000000000..67251ca6aa9b
--- /dev/null
+++ b/users/wpcarro/scratch/rust/src/rc/mod.rs
@@ -0,0 +1,12 @@
+// Playing around with Rust's "smart pointers". Starting off with a wrapper type
+// that allows multiple readers (owners?) of some data.
+
+use std::rc::Rc;
+
+pub fn example() {
+    let five = Rc::new(5);
+    let x = Rc::clone(&five);
+    let y = Rc::clone(&five);
+    let z = Rc::clone(&five);
+    println!("result: {}", *x + *y + *z)
+}
diff --git a/users/wpcarro/scratch/rust/src/stdin/mod.rs b/users/wpcarro/scratch/rust/src/stdin/mod.rs
new file mode 100644
index 000000000000..4be95afa4547
--- /dev/null
+++ b/users/wpcarro/scratch/rust/src/stdin/mod.rs
@@ -0,0 +1,22 @@
+use std::io::Write;
+use std::process::{Command, Stdio};
+
+// Example of piping-in a string defined in Rust to a shell command.
+pub fn example() {
+    let input = "Hello, world!";
+
+    let mut cat = Command::new("cat")
+        .stdin(Stdio::piped())
+        .spawn()
+        .ok()
+        .unwrap();
+
+    cat.stdin
+        .take()
+        .unwrap()
+        .write_all(&input.as_bytes())
+        .unwrap();
+
+    let output = cat.wait_with_output().unwrap();
+    println!("{}", String::from_utf8_lossy(&output.stdout));
+}