Alfie 2: Alfie Harder

Samir Talwar
Dec 7, 2018 · 2 min read

We’ve been iterating on Alfie obsessively for a week and a bit since the last post, and I wanted to share what’s going on.

The most notable update is performance. Advent of Code was a hard lesson for us — Alfie kept choking on running solutions on large inputs. The tracer now operates in constant time (with regards to a single trace), meaning that we can handle data of any size without much bottleneck, and the trace itself is much faster. We’re now about 1.5✕ slower than just running the JavaScript in the browser console, down from WAY_TOO_SLOW.

The home page is now way more helpful, teaching you how Alfie works, what you can do with it, and why it matters. Check it out. 😁


The traces themselves have improved a lot. We now handle the lesser-known data structures such as Map and Set, they’re properly formatted in tables so they’re easier to follow, and we get to the heart of the actual data whenever possible. This is mostly down to your feedback, so keep sending it in!

We’re really thankful that so many of you are enjoying Alfie and telling us what you’re doing with it. We found out one of you made a Slackbot with it the other day, which is incredible. 😮 We’ve added a Share button so you can share your work with your friends. You could always share the link, but now it’s way easier.

So if you make something cool, something you’re proud of, or something you think is hilarious, please send the link or a screenshot our way. We’d love to see it! You can reach us on Twitter at @ProdoAI or by email — it’s

Have a great weekend, everyone. Happy scripting! 👩🏾‍💻👨🏼‍💻

It’s Friday night. Izzy is exhausted. And adorable.

We write code for humans.

We write code for humans.

Samir Talwar

Written by

CTO at Prodo.AI. I make machines go beep boop.

We write code for humans.