I'm J.R. Hill and I code mostly for fun. (No, really!)

I'm currently serving as a Staff Software Engineer at Onward, an energy, geoscience, and climate innovation company.

My longest-running gig in the software industry was 9 years at Amazon between 2014 and 2023. I was a core maintainer of the company's internal software ecosystem. I owned, personally as a single engineer, tens of thousands of software projects (libraries, daemons, templates, executables, etc) used directly and transitively by AWS, Amazon.com, MGM, Twitch, Kindle, Audible, IMDB, Comixology, Whole Foods, Zappos, and more. Applications ranged from the web, fintech, adtech, embedded and IoT, consumer devices, avionics, robotics, satellites and more. I'm not a rocket scientist, but my code has been to space.

The rest of this page is dedicated to non-proprietary work.


The following personal works are ordered roughly by the level of interest I've seen.

Projects with a + after the year are projects that I actively think about and work on. Projects without a + after the year are relatively stable; I may still make an occasional update, but I'm not thinking about them or planning more work for them.

Tools & Languages

dt 2022+ Zig Rust It's duck tape for your unix pipe. A straightforward concatenative functional language for Unix-like shells.
sigi 2021+ Rust An organizational tool for people (like me) who hate organizing.
stap 2023 Rust An interpreted, concatenative LISP programming language.
findup 2021+ Zig A simple tool for finding your way back 'up' to places like a project root.
fib 2021 Haskell A tool for getting fibonacci numbers, using all the best tricks of Haskell.
yaml2toml 2021 Python A tool that turns yaml into toml. (Yes, yj is better.)


Z 2021+ Java Fuse functions together.
Levee 2022 Java A Java library with a general-purpose singleton implementation.
Pair 2022 Java A simple pair and drop-in shim for the beloved javafx.util.Pair class that was included in JDK 8. (And is still available in the JavaFX project)
Singleton 2021 Java A Java library with a general-purpose singleton implementation.


hello 2020+ Various A collection of a few compilable 'Hello world' apps. Intended as a resource for comparing languages like C, Forth, COBOL, and others. (For so much more, see Rosetta Code.)
Link Alchemizer 2022 JavaScript A web utility for opening many permutations of URLs.
Tiny Puppy RPG 2010 ActionScript 3 A game in which you are a tiny puppy, and must fetch a bone.

Experimental & Unfinished

Rail 2021+ Rust A concatenative programming language and virtual stack machine. Not looking to be stable any time soon. Forms the basis of dt.
Jumble 2022+ Java A library for collections with independently typed items. Began as a research project for Z.
Lyle 2022+ Rust? An (unofficial) assembler for processors compatible with the Xtensa instruction set architecture. This is the instruction set used by the popular ESP32 and ESP8266 chips, among others.


Find my games at booniepepper.itch.io

I'm currently tracking down older games that I hope are lying around.

I have a list of games I'm trying to find here and am searching various machines and disks that I've got, but it will be a slow process. If anyone comes across something here, please let me know!

Public Solutions

The following are solutions to various online coding challenges. Sometimes challenges get updated, so these may become out of date. They were working at the time of commit.

These are intended as a learning resource. Please don't cheat yourself out of learning. More sites and more languages to come.


Certifications from Codingame.