<<loop>> exception about reactive-banana HOT 3 CLOSED

Thanks for your report, Aleksey!

Unfortunately, it's not a bug, it's a feature. :-) The semantics of the changes function has slightly deteriorated in reactive-banana-0.7.

As indicated in the documentation, it's not possible to access the value that has changed until after event processing is complete. This means that things are ok if you put it more or less directly into a reactimate, but trying to inspect the value during event processing will throw the program into an infinite loop.

In your case, the accumE function is strict in the event values and the acc performs a pattern match on the value obtained from changes. Hence, the listEvents function goes into an infinite loop.

Essentially, the changes function only exists to bridge between the FRP and the IO world. The semantics of the Behavior type itself does not support a notion of "this behavior just changed".

Is this hardship acceptable to you?

from reactive-banana.

I see. Such subtle changes are always pain. I think I can solve my problem without using changes. I didn't like it because of unclear semantics but it kind of worked before.

Also could you please write changelogs. It's hard to find such changes. AFAIR new hackage2 will have special location for them. It's currently in testing

from reactive-banana.

I actually do write a small changelog, but it should probably displayed at a more prominent position. :-)

from reactive-banana.