# Tomorrow: "Pacman" Continuations

**URL:** <https://racket.discourse.group/t/tomorrow-pacman-continuations/4190>\
**Category:** General\
**Tags:** qi, meet-up\
**Created:** [April 17, 2026, 4:42am UTC](https://racket.discourse.group/t/tomorrow-pacman-continuations/4190 "2026-04-17T04:42:38Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![countvajhula](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/countvajhula/32/65_2.png) [@countvajhula](https://racket.discourse.group/u/countvajhula)\
**Post date:** [April 17, 2026, 4:42am UTC](https://racket.discourse.group/t/tomorrow-pacman-continuations/4190/1 "2026-04-17T04:42:38Z")

</div>

Hello friends,  
Tomorrow in the regular Qi meeting we will be talking about some recent developments that are likely to be of broad interest, including:

- A proof-of-concept (in fact, two of them, using totally separate approaches) of achieving "multi-streams" in Qi, that is, streams that can yield any number of values at any step, to provide performant deforested functional operations on sequential data.
- Progress on implementing deforested list APIs that mirror `racket/list`, including potentially a standalone library `ebb` that provides this for your ordinary Racket code.
- Considerations around stream vs list semantics for the design of functional APIs.

The multi-streams proof-of-concept is my first deep dive into the continuation-passing style, and I'm eager to share my learnings. The approach we're using to achieve multi-streams is neat --- some tentative names we have for it include "Pacman continuations" and "Call stack Tetris." Join us tomorrow to learn more 🙂

Please stop by if any of these sound interesting to you.

2026-04-17T18:00:00Z

> **[Jitsi Meet](https://meet.jit.si/Racketmeet-up)**
>
> Join a WebRTC video conference powered by the Jitsi Videobridge

(Please note: if you join before an admin gets there, you might need to refresh your browser subsequently to end up in the same meeting as the other attendees!)

Sid & the Qiwis

---

<div class="post-metadata">

**Author:** ![countvajhula](https://yyz2.discourse-cdn.com/free1/user_avatar/racket.discourse.group/countvajhula/32/65_2.png) [@countvajhula](https://racket.discourse.group/u/countvajhula)\
**Post date:** [April 18, 2026, 9:58am UTC](https://racket.discourse.group/t/tomorrow-pacman-continuations/4190/2 "2026-04-18T09:58:19Z")

</div>

For anyone following along:

[Design document for the "Pac-Man" approach](https://countvajhula.com/oldsite/qi/pacman/)  
[Runnable code](https://gist.github.com/countvajhula/8feb1e7a1cf89dedc5fa0142083255c9)  
[An alternative (and maybe even faster?) "list-builder" approach in the ebb library](https://gitlab.com/racketeer/ebb/-/blob/master/ebb-lib/base.rkt?ref_type=heads)

Feedback welcome.

Enjoy,