reactive-banana and behavior lag, among other things

backstory: i've been using the reactive-banana FRP library to handle the i/o for my haskell stuff, because if you recall i spent one of these two-week projects hacking together a haskell-style i/o management setup that i kept tying myself into knots with and eventually somebody was like "this sounds like you're reinventing the concept of FRP and you should maybe use one of these libraries". then i got wrapped up in trying to comprehend how reactive-banana works and is expected to be used, and how you can practically use it to do things. it's not exactly the most clear, so i figure it's worth it to post about my HARD-EARNED UNDERSTANDING of how it works.

( this post assumes that you basically understand haskell and that you've used reactive-banana enough to have some problems with it. )