what is a good name for a function that takes an "event", and returns either a nil, which means the event should be ignored, or some value, which will be "reemitted" as an event to an upper layer? This function will be provided by the upper layer, so I'm looking for a good parameter-name

reemit? … ?

i'm thinking something along the lines of should-propagate?

@gusbicalho: that has the same semantics as keep, so given that is taken what about keep-event?

@colin.yates that sounds good, I didn't know keep