It seems that the function 'justE' caused my problem.
If I remove that, replacing the section at issue with

  exitE = fmap esc ky where
    esc k = case k of
      Char '\ESC' -> exitSuccess
      _           -> nop

then the program works. However, there is a large
random delay, sometimes measured in seconds, before
processing the events in the second argument of
`mappend`. And it still leaks space. Any advice?
(all this is with reactive-0.9.6 and ghc 6.10.1)

Thanks,
Balazs

On Tue, Dec 2, 2008 at 1:58 PM, Balazs Komuves <bkomuves@gmail.com> wrote:

Dear All,

I'm trying to get my hands wet with the reactive library,
but already the simplest example I cooked up is failing
to work properly (and leaks memory, and uses relatively
lots of cpu time).

The problem appears when I try to merge my two events
with `mappend`. One event should exit on pressing ESC,
the other draws colored circles on pressing the left mouse
button. They work correctly separately.

Could somebody explain me what's happening, or
whether I'm making a basic mistake?

The code is below, I hope the formatting survives the
various email systems. I don't know if that matters or
not, but I'm using OS X.

Thanks,
Balazs