Simon Willison’s Weblog

Subscribe
Atom feed for sam-rose

4 posts tagged “sam-rose”

2025

Sam Rose explains how LLMs work with a visual essay. Sam Rose is one of my favorite authors of explorable interactive explanations - here's his previous collection.

Sam joined ngrok in September as a developer educator. Here's his first big visual explainer for them, ostensibly about how prompt caching works but it quickly expands to cover tokenization, embeddings, and the basics of the transformer architecture.

The result is one of the clearest and most accessible introductions to LLM internals I've seen anywhere.

Animation. Starts in tokens mode with an array of 75, 305, 24, 887 - clicking embeddings animates those into a 2D array showing each one to be composed of three floating point numbers.

# 19th December 2025, 6:33 pm / ai, explorables, generative-ai, llms, sam-rose, tokenization

Reservoir Sampling (via) Yet another outstanding interactive essay by Sam Rose (previously), this time explaining how reservoir sampling can be used to select a "fair" random sample when you don't know how many options there are and don't want to accumulate them before making a selection.

Reservoir sampling is one of my favourite algorithms, and I've been wanting to write about it for years now. It allows you to solve a problem that at first seems impossible, in a way that is both elegant and efficient.

I appreciate that Sam starts the article with "No math notation, I promise." Lots of delightful widgets to interact with here, all of which help build an intuitive understanding of the underlying algorithm.

Animated demo. As a slider moves from left to right the probability of cards drawn from a deck is simulated. Text at the bottom reads Anything older than 15 cards ago is has a less than 0.01% chance of being held when I stop.

Sam shows how this algorithm can be applied to the real-world problem of sampling log files when incoming logs threaten to overwhelm a log aggregator.

The dog illustration is commissioned art and the MIT-licensed code is available on GitHub.

# 8th May 2025, 9 pm / algorithms, logging, rate-limiting, explorables, sam-rose

2024

Load Balancing. Sam Rose built this interactive essay explaining how different load balancing strategies work. It's part of a series that includes memory allocation, bloom filters and more.

# 13th July 2024, 10:51 pm / algorithms, load-balancing, explorables, sam-rose

Bloom Filters, explained by Sam Rose. Beautifully designed explanation of bloom filters, complete with interactive demos that illustrate exactly how they work.

# 23rd February 2024, 3:59 pm / bloom-filters, explorables, sam-rose