(not) catching ^C in ghc-built application

[Malcolm Wallace]

> > My best guess is that the use of signal() is incompatible with the
> > POSIX sigaction() used by the RTS.
> 
> That's possible I guess.  Could you try using sigaction() instead?

No change in behaviour.  Is it possible that ghc's scheduler might be
re-installing signal handlers throughout the computation whenever it
has control?  For instance, if threads are allocated fixed processor
time via the VTALRM signal, maybe when the alarm timer is restored?
I had a quick look at ghc/rtc/Itimer.c, but this hypothesis doesn't
look very likely.

Regards,
    Malcolm