"Controlling Time and Space: understanding the many formulations of FRP" by Evan Czaplicki
Why Hacker News recommends it
HN people point to it as the clearest explanation of what FRP actually means and how its flavors differ.
What it is
Evan Czaplicki's Strange Loop 2014 talk surveys the many formulations of functional reactive programming and how they relate historically and theoretically. It then shows how Elm's variant enables hot-swapping and its time-traveling debugger.
Recommended by 5 HN commenters across 5 different months, 2014 to 2026.
What Hacker News said
Strong rec dcre · 2014-12 · on “Elm 0.14 – Simpler Core, Better Tools”
If you're interested in Elm but don't really know what it's about, I highly recommend Evan's Strange Loop talk, "Controlling Time and Space: understanding the many formulations of FRP." It will help to already have a bit of background in functional programming. [this video]
Strong rec modulovalue · 2026-03 · on “We've had front end reactivity since 2018 – via Async Iterables”
There's an important issue with async iterables: what's the initial value of derived "signals"? In the Dart/Flutter world, async iterables are known as streams. The biggest problem is that they are asynchronous so if you derive new streams from existing streams, you won't have a value immediately for those streams available, you'll have to wait a frame for values to propagate. That's not a problem if you're just processing data, but if you're using them in a UI framework and your UI framework is coupled to the event loop, then you have a problem. This doesn't happen with the ReactiveX approach because things are evaluated immediately, one doesn't have to wait for the event loop to tick. (A f
Recommends platz · 2014-11 · on “Introduction to Reactive Programming”
> "FRP is programming with asynchronous data streams." Maybe, if you drop the F. For clarification on FRP there was a great talk at strangeloop this year: [this video]
Recommends michaelsbradley · 2015-11 · on “React vs. Angular 2”
It's been around in various forms, and implemented on top of various languages, for quite some time. The earliest full-fledged FRP implementation for JavaScript was Flapjax – work on it dates all the way back to 2006! [LINK] The paper Flapjax: A Programming Language for Ajax Applications is worth reading. [LINK] The principal designer and maintainer of the Elm Language (a functional reactive lang that compiles to JS) did his Master's Thesis on FRP, and that's a great resource if you want the big picture: [LINK] See also Controlling Time and Space: understanding the many formulations of FRP , by the same author: [this video]
Recommends ghuntley · 2016-01 · on “New Adventures for Elm”
For those just getting started in FRP or whom may have not seen the presentations at StangeLoop: - [this video] - Controlling Time and Space: understanding the many formulations of FRP by Evan Czaplicki (Elm language designer/Prezi) - [LINK] - FRP In Practice: Taking a look at Reactive[UI/Cocoa] by Paul Betts (Slack/GitHub) - [LINK] - ReactiveUI - It's pretty neat by Brendan Forster (GitHub)
Cites jarpineh · 2015-08 · on “A simpler web architecture using React, Flux, CSP, and FRP concepts”
Higher level concepts in area so rife with incidental complexity like programming tend to get lost in the details of the implementation. Patterns and abstract concepts like FRP can only be understood by with implementation. Ideas tend to bend before working code, then again with an example app you enthusiastically write for your blog, and then again when someone bases her next project on that (not to mention HN discussions...). I like to learn thing this way, and not care that much about what the alphabet soup entails. Try to find what is a proper JavaScript MVC framework. And then write the first one yourself ;) I'm currently reading Clojure Reactive Programming, which differentiates from F
Cites ghuntley · 2015-08 · on “Ask HN: Why web frameworks are becoming so complex?”
> The web community pioneered UI development paradigms involving > functional programming techniques and immutable data Ugh, No. [LINK] and [this video]
Cites goldenkey · 2015-08 · on “Ask HN: Why web frameworks are becoming so complex?”
I appreciate your resources, namely the video by the creator of Elm, [this video] . However, I agree with above poster. I remember developing my first windows app by doing a main event loop. It's been that way for a long time. Only recently are we doing more asychronous callback / bound type mechanisms of reaction. And still not as strong as the FLP stuff mentioned in the video. Not as much functional stuff, just functional paradigms. I personally really like the perfection of static input/output transformation graphs. But yeah..it's not been that way for a while and I agree with OP, the web being so event/input/signal based, has spurred the movement for better ways of reactive programming.