keyQ = filterE (== 'q') . keyEvent keyA = filterE (== 'a') . keyEvent
testWire2 = hold . (keyQ &> keyA)
This is the problem. You actually have the 'keyEvent' wire twice in there, which means that both are trying to take from the 'MVar', which in turn means that in any frame if keyQ gets nothing, it's very unlikely that keyA will get something (because it runs pretty much directly after keyQ), and whenever keyQ gets something, it will clear the MVar, so keyA gets nothing again. The real solution is not to have keyEvent twice in there: proc _ -> do keys <- keyEvent -< () qKeys <- filterE (== 'q') -< keys aKeys <- filterE (== 'a') -< keys hold -< mergeL qKeys aKeys Perhaps you would like to try the new [wires] library, which has a much cleaner distinction between frameworks and the actual FRP description, so mistakes like this are far less likely. It's a cleaner library than Netwire in general. =) [wires]: https://hackage.haskell.org/package/wires Greets ertes