Stream: show and tell

Topic: FastTrack board game

Steve Howell (Sep 24 2026 at 12:22):

About seven years my mother introduced me to a board game called FastTrack that she and her friends from her retirement community play. It's a board game where you use your playing cards to make moves that take your marbles out of your "pen", around the board, and then back to your "base". It's a good social game--it's mostly luck that determines the winner among good players, but there's just enough strategy to keep it interesting.

Back in 2019 I created an online version of the game using Elm. During the last couple days I had Claude (Opus 5.5 mostly!) port it to Roc. The big addition that Claude made is that you now play against three "computer" opponents--the "agents" use a Roc-based search algorithm to make their best moves.

Steve Howell (Sep 24 2026 at 12:25):

You can play the game here: https://roc.lynrummy.com/fasttrack/

Here are is a screencast of the agents playing:

fasttrack.mp4

Steve Howell (Sep 24 2026 at 12:30):

Details on the port:

• Claude ported Elm to Roc with great ease.
• The JS layer is very light.
• We found a few bugs with Roc that are now filed as issues.
• Roc is fast enough to do 2000-game trials in reasonable time to tune the agent-play algorithms, but it's important to use the right builds and be somewhat careful about data structures.

Claude wrote about it here: http://143.244.172.148:9100/notes/fasttrack-in-roc.md

Steve Howell (Sep 24 2026 at 12:34):

The whole game is 4399 lines of Roc as of this writing, which includes comments, tests, agent-play-experiment harnesses, as well as the game itself. :)

Steve Howell (Sep 24 2026 at 12:35):

The JS layer is only 310 lines (including comments) and the HTML shell is only 18 lines. So Roc is doing all the heavy lifting here.

Steve Howell (Sep 24 2026 at 12:38):

On my main Roc demo page I now have at least ten apps that all follow the same pattern:

• write your browser app primarily in Roc (compiled to wasm)
• add a thin layer of hand-written JS (often with Roc-glue-generated JS at the boundary)
• use Roc natively for things like roc-ray variants, headless testing, algorithm exploration, interpreter verification, etc.

Steve Howell (Sep 24 2026 at 12:41):

The code is here: https://github.com/showell/roc-apps/tree/master/fasttrack

Last updated: Sep 24 2026 at 15:59 UTC