8 ms·

Scoped Propagators

164 points by cdata 2y ago

donpark 2y ago
Related repos: https://github.com/OrionReed/scoped-propagators https://github.com/OrionReed/scoped-propagators https://github.com/dennishansen/holograph https://github.com/dennishansen/holograph
zoogeny 2y ago
This kind of node/edge based programming model is one I've been interested to see applied to LLMs. In some sense, we can see the input of an LLM as a node, the LLM itself as a function describing the edge of the graph, and the output of the LLM as a new node.
noelwelsh 2y ago
Some of the videos are broken for me (using Firefox). Otherwise looks pretty neat. Compared to FRP it is perhaps a bit more declarative in the definition of scopes, but otherwise seems equivalent. I'm interested in more details on this. I'm also a bit confused by > This model has not yet been formalised, and while the propagators themselves can be simply expressed as a function ... I have not yet found an appropriate way to express scopes and the relationship between the two. This seems straightforward to me (e.g. a scope could be a set of types, where each distinct event has a distinct type) so I think I'm missing something here.
- aag 2y ago
  All but two of the videos are broken for me on both Chrome and Firefox. I would love to see the rest! I encourage people to read the original Propagator Networks paper by Alexey Radul (advisor: Prof. Gerald Sussman of SICP) referenced in the Prior Work section. It's full of fascinating ideas. https://dspace.mit.edu/handle/1721.1/54635 https://dspace.mit.edu/handle/1721.1/54635
  - orionreed 2y ago
    Would love to know which videos are broken and any other details so I can try and fix that!
    - jedharris 2y ago
      None of the MP4 videos play in Firefox. The MOV videos play fine. All the videos play in Safari. I have not tried Chrome.
      - mjcohen 2y ago
        The same thing seems to apply for Zoom background videos.
      - orionreed 2y ago
        good to know! seems that I'm using encodings for those which Firefox does not support https://stackoverflow.com/questions/73855321/why-wont-mp4-video-work-with-html5-video-tag-on-firefox https://stackoverflow.com/questions/73855321/why-wont-mp4-vi...
    - Kikawala 2y ago
      Firefox doesn't support H.265/HEVC. bridging.mov and examples.mp4 are working as they are H.264/AVC, the other videos are H.265/HEVC
    - SrslyJosh 2y ago
      None of the videos played for me in Safari 16. =(
  - davexunit 2y ago
    Yeah I can't see most of the videos, either. :( I absolutely love Alexey Radul's dissertation. So interesting to see this article show up on the HN front page after I just published my own experiment with propagators yesterday: https://dthompson.us/posts/functional-reactive-user-interfaces-with-propagators.html https://dthompson.us/posts/functional-reactive-user-interfac... I need to learn more about the design decisions behind scoped propagators and why they deviate from "regular" propagators.
  - Yen 2y ago
    As a workaround in firefox, I was able to right-click, "save video as", and open in VLC.
- davexunit 2y ago
  > Compared to FRP it is perhaps a bit more declarative in the definition of scopes, but otherwise seems equivalent. FRP systems are typically limited to acyclic graphs. The system in this article allows for cycles.
  - themk 2y ago
    Every FRP system I've used allows cycles.
    - davexunit 2y ago
      Such as?
blixt 2y ago
Very cool! Good to see the shoutout to Dennis' Holograph.so work as well. I played around with that one to make some fun things: A game of cat and mouse: https://x.com/blixt/status/1797384954172625302 https://x.com/blixt/status/1797384954172625302 An analog clock: https://x.com/blixt/status/1798393279194824952 https://x.com/blixt/status/1798393279194824952 I think tools like these, with better UX and more guard rails for the code, can really help people understand logic and systems in a much more visually intuitive way. In some aspects, these propagators work similar to Excel, which I think a lot of people already have some intuition for.
graypegg 2y ago
Interesting concept! It does remind me of the observables somewhat, where nodes are functions, which accept data coming in from events, which it transforms, and then chooses to emit new values or not. This flips that, so nodes are data, which accept functions from events, it applies that function to itself, then decides to propagate that event onwards or not. I like it! That model works really well for this sort of visual programming demoed in the infinite canvas stuff.
- chatmasta 2y ago
  I only glanced at the article, but it also reminds me of Dataflow programming, incrementally updated materialized views, etc. (all the same concept at the end of the day, and yes, very similar to observables)
  - CyberDildonics 2y ago
    It remind you of dataflow programming because it's literally the same thing.
    - thechao 2y ago
      Specifically, the application of dataflow to GUIs, which was well-researched at Adobe by Sean Parent, Mat Marcus, et al in the early 2000s called the "Adam" and "Eve" languages. There's more work at TAMU & University of Turku (by Jaakko Jarvi) under the name "Espresso", or something like that. Basically, the "scopes" become constraints, and they use a hierarchical constraint solver to propagate state changes to the GUI elements, real-time, using a declarative dataflow programming model.
  - davexunit 2y ago
    As Gerald Sussman says in "We really don't know how to compute!": > It's not dataflow! It's closely related, but it's not. https://youtu.be/HB5TrK7A4pI?t=2071 https://youtu.be/HB5TrK7A4pI?t=2071
- CyberDildonics 2y ago
low_tech_punk 2y ago
Reminds me of Gerald Sussman's talk "We Really Don't Know How to Compute!" (2011) https://youtu.be/HB5TrK7A4pI?si=99cUwmS_03VwLUP7&t=2038 https://youtu.be/HB5TrK7A4pI?si=99cUwmS_03VwLUP7&t=2038
GrantMoyer 2y ago
As written, a "scope" is a function, s: G² → None + T, from the current global state and the previous global state to an optional value of some type T. Meanwhile, a "propagator" is a function, p: G² × A × B → B, from the current global state, the previous global state, a source node, and a target node to a new target node, such that p(g, g', a, b) = if s(g, g') is None then b else f(s(g, g'), a, b) for some f: T × A × B → B. For example tick(g, g') = time(g') - time(g), and change(g, g') = if node_s(g') ≠ node_s(g) then () else None where node_s(g) gets the source node of the change scope from global state g. In practice the outputs of a scope can be computed once per state change and called an event, rather than computed on demand each time it's used, and scopes which return None don't need to be propagated. Also, I suspect it would be useful to restrict scopes to (A × B)² → None + T or even just A² → None + T, so that events are limited to propagating along chains of edges.
MurrayHurps 2y ago
This is genius, and very well described. Could be a meaningful bridge between “nocode” and code, avoiding what seems like a common pain point of eventual nocode limitations. I know there are other solutions in this space, but yours is very nicely done. Please continue work on this, and yell out if you need collaborators.
omneity 2y ago
What is separating this concept from dataflow programming, perhaps with slightly different semantics and interaction patterns? (I reckon my understanding might be limited so I'm genuinely seeking enlightenment)
jiggawatts 2y ago
This feels very similar to how database table triggers work. You define trigger conditions, and then the trigger on table A tells table B how to update itself. The tables store only data.
hosh 2y ago
Wow! That's neat! There are a lot to explore beyond interactive objects. One of the first thing that comes to mind was is about Smalltalk, and the idea that it is about the messages and not the objects. The next thing to come in mind is about how this allows for composition of interactions. I think it can enable highly local customization that can still receive software updates from upstream. I am thinking about how one of the problems with extensible specifications (such as XMPP) eventually lead to an ecosystem where feature updates cannot propogate easily; and we might see something like that in the Fediverse
fiddlerwoaroof 2y ago
This seems like delimited continuations to me

164 points by cdata 2y ago

Related repos: https://github.com/OrionReed/scoped-propagators https://github.com/OrionReed/scoped-propagators https://github.com/dennishansen/holograph https://github.com/dennishansen/holograph

zoogeny 2y ago

This kind of node/edge based programming model is one I've been interested to see applied to LLMs. In some sense, we can see the input of an LLM as a node, the LLM itself as a function describing the edge of the graph, and the output of the LLM as a new node.

noelwelsh 2y ago

Some of the videos are broken for me (using Firefox). Otherwise looks pretty neat. Compared to FRP it is perhaps a bit more declarative in the definition of scopes, but otherwise seems equivalent. I'm interested in more details on this. I'm also a bit confused by > This model has not yet been formalised, and while the propagators themselves can be simply expressed as a function ... I have not yet found an appropriate way to express scopes and the relationship between the two. This seems straightforward to me (e.g. a scope could be a set of types, where each distinct event has a distinct type) so I think I'm missing something here.

aag 2y ago
All but two of the videos are broken for me on both Chrome and Firefox. I would love to see the rest! I encourage people to read the original Propagator Networks paper by Alexey Radul (advisor: Prof. Gerald Sussman of SICP) referenced in the Prior Work section. It's full of fascinating ideas. https://dspace.mit.edu/handle/1721.1/54635 https://dspace.mit.edu/handle/1721.1/54635
- orionreed 2y ago
  Would love to know which videos are broken and any other details so I can try and fix that!
  - jedharris 2y ago
    None of the MP4 videos play in Firefox. The MOV videos play fine. All the videos play in Safari. I have not tried Chrome.
    - mjcohen 2y ago
      The same thing seems to apply for Zoom background videos.
    - orionreed 2y ago
      good to know! seems that I'm using encodings for those which Firefox does not support https://stackoverflow.com/questions/73855321/why-wont-mp4-video-work-with-html5-video-tag-on-firefox https://stackoverflow.com/questions/73855321/why-wont-mp4-vi...
  - Kikawala 2y ago
    Firefox doesn't support H.265/HEVC. bridging.mov and examples.mp4 are working as they are H.264/AVC, the other videos are H.265/HEVC
  - SrslyJosh 2y ago
    None of the videos played for me in Safari 16. =(
- davexunit 2y ago
  Yeah I can't see most of the videos, either. :( I absolutely love Alexey Radul's dissertation. So interesting to see this article show up on the HN front page after I just published my own experiment with propagators yesterday: https://dthompson.us/posts/functional-reactive-user-interfaces-with-propagators.html https://dthompson.us/posts/functional-reactive-user-interfac... I need to learn more about the design decisions behind scoped propagators and why they deviate from "regular" propagators.
- Yen 2y ago
  As a workaround in firefox, I was able to right-click, "save video as", and open in VLC.
davexunit 2y ago
> Compared to FRP it is perhaps a bit more declarative in the definition of scopes, but otherwise seems equivalent. FRP systems are typically limited to acyclic graphs. The system in this article allows for cycles.
- themk 2y ago
  Every FRP system I've used allows cycles.
  - davexunit 2y ago
    Such as?

blixt 2y ago

Very cool! Good to see the shoutout to Dennis' Holograph.so work as well. I played around with that one to make some fun things: A game of cat and mouse: https://x.com/blixt/status/1797384954172625302 https://x.com/blixt/status/1797384954172625302 An analog clock: https://x.com/blixt/status/1798393279194824952 https://x.com/blixt/status/1798393279194824952 I think tools like these, with better UX and more guard rails for the code, can really help people understand logic and systems in a much more visually intuitive way. In some aspects, these propagators work similar to Excel, which I think a lot of people already have some intuition for.

graypegg 2y ago

Interesting concept! It does remind me of the observables somewhat, where nodes are functions, which accept data coming in from events, which it transforms, and then chooses to emit new values or not. This flips that, so nodes are data, which accept functions from events, it applies that function to itself, then decides to propagate that event onwards or not. I like it! That model works really well for this sort of visual programming demoed in the infinite canvas stuff.

chatmasta 2y ago
I only glanced at the article, but it also reminds me of Dataflow programming, incrementally updated materialized views, etc. (all the same concept at the end of the day, and yes, very similar to observables)
- CyberDildonics 2y ago
  It remind you of dataflow programming because it's literally the same thing.
  - thechao 2y ago
    Specifically, the application of dataflow to GUIs, which was well-researched at Adobe by Sean Parent, Mat Marcus, et al in the early 2000s called the "Adam" and "Eve" languages. There's more work at TAMU & University of Turku (by Jaakko Jarvi) under the name "Espresso", or something like that. Basically, the "scopes" become constraints, and they use a hierarchical constraint solver to propagate state changes to the GUI elements, real-time, using a declarative dataflow programming model.
- davexunit 2y ago
  As Gerald Sussman says in "We really don't know how to compute!": > It's not dataflow! It's closely related, but it's not. https://youtu.be/HB5TrK7A4pI?t=2071 https://youtu.be/HB5TrK7A4pI?t=2071
CyberDildonics 2y ago

low_tech_punk 2y ago

Reminds me of Gerald Sussman's talk "We Really Don't Know How to Compute!" (2011) https://youtu.be/HB5TrK7A4pI?si=99cUwmS_03VwLUP7&t=2038 https://youtu.be/HB5TrK7A4pI?si=99cUwmS_03VwLUP7&t=2038

GrantMoyer 2y ago

As written, a "scope" is a function, s: G² → None + T, from the current global state and the previous global state to an optional value of some type T. Meanwhile, a "propagator" is a function, p: G² × A × B → B, from the current global state, the previous global state, a source node, and a target node to a new target node, such that p(g, g', a, b) = if s(g, g') is None then b else f(s(g, g'), a, b) for some f: T × A × B → B. For example tick(g, g') = time(g') - time(g), and change(g, g') = if node_s(g') ≠ node_s(g) then () else None where node_s(g) gets the source node of the change scope from global state g. In practice the outputs of a scope can be computed once per state change and called an event, rather than computed on demand each time it's used, and scopes which return None don't need to be propagated. Also, I suspect it would be useful to restrict scopes to (A × B)² → None + T or even just A² → None + T, so that events are limited to propagating along chains of edges.

MurrayHurps 2y ago

This is genius, and very well described. Could be a meaningful bridge between “nocode” and code, avoiding what seems like a common pain point of eventual nocode limitations. I know there are other solutions in this space, but yours is very nicely done. Please continue work on this, and yell out if you need collaborators.

omneity 2y ago

What is separating this concept from dataflow programming, perhaps with slightly different semantics and interaction patterns? (I reckon my understanding might be limited so I'm genuinely seeking enlightenment)

jiggawatts 2y ago

This feels very similar to how database table triggers work. You define trigger conditions, and then the trigger on table A tells table B how to update itself. The tables store only data.

hosh 2y ago

Wow! That's neat! There are a lot to explore beyond interactive objects. One of the first thing that comes to mind was is about Smalltalk, and the idea that it is about the messages and not the objects. The next thing to come in mind is about how this allows for composition of interactions. I think it can enable highly local customization that can still receive software updates from upstream. I am thinking about how one of the problems with extensible specifications (such as XMPP) eventually lead to an ecosystem where feature updates cannot propogate easily; and we might see something like that in the Fediverse

fiddlerwoaroof 2y ago

This seems like delimited continuations to me