Re: [Haskell-cafe] Announcement - HGamer3D - 0.2.1 - why netwire

Ertugrul Söylemez wrote:

Heinrich Apfelmus wrote:

...

You said that reactive-banana didn't feel as simple after the introduction of dynamic event switching, though. Could you pinpoint some particular thing that made you feel like that? Maybe a type signature or a tutorial or something else? I took great care trying to make the dynamic event switching stuff entirely optional, so you can use reactive-banana without understanding it at all, but I'm not sure if I succeeded.

I think this is less of an issue with reactive-banana than with classic FRP in general. The type signatures of Netwire can be scary at first sight, but they are consistent throughout the entire library. Once you understand one of these type signatures you understand all of them. Once you know how to use one wire, you know how to use all others.

Let me pinpoint something in particular: events. In reactive-banana events are special, in Netwire they are not. This makes dynamic switching special in reactive-banana and natural in Netwire. Let me show you an example: You want to dispaly "one" for ten seconds, then "two" for twelve seconds, then start over:

myWire = "one" . for 10 --> "two" . for 12 --> myWire

Events and particularly dynamic event switching is one of the main problems Netwire solves elegantly. You can add this to reactive-banana, too, but it would require changing almost the entire event interface.

I concur that chaining wires with the andThen combinator is very slick, I like it a lot. Wolfgang Jeltsch recently described a similar pattern for classical FRP, namely a behavior that doesn't live forever, but actually ends at some point in time, which can be interpreted as an event occurrence. ("It ends with a bang!") However, do note that the andThen combinator in netwire can only be so slick because "switching restarts time" (as the documentation puts it). I don't see a nice way to switch between wires that have accumulated state. How would you express the TwoCounters example [1] using dynamic event switching in netwire? (The example can be implemented without dynamic event switching, but that's not what I mean.) What about the BarTab example [2]? [1]: http://www.haskell.org/haskellwiki/Reactive-banana/Examples#twoCounters [2]: http://www.haskell.org/haskellwiki/Reactive-banana/Examples#bartab Best regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com