On Tue, May 24, 2011 at 14:48, Artem Chuprina <ran-ghu@ran.pp.ru> wrote:

An author writes that the code was tested on ghc 6.6 under Linux/x86. I have
ghc 6.12.1 on Debian GNU/Linux. My compiler asked me to add type signatures
in second arguments of catch (original code does not have them).

The latter sounds like new vs. old exceptions. The former, I think this is a known bug in 6.12.1.