On Thu, Mar 01, 2007 at 04:21:45PM +0000, Simon Marlow wrote: > >Between that and the lack of support for forkProcess in Hugs, this > >renders anything that needs to fork and then do I/O as being usable only > >in GHC-compiled code. Which is sub-optimal, but livable anyway. > > I guess I'm really wondering why you need to fork and do I/O at all. Can > you describe the problem at a higher level?
I am, for all intents and purposes, writing what amounts to a simple shell. The standard way of implemeting pipes between two external programs in Unix involves setting up pipes and forking, then duping things to stdin/stdout, and execing the final program. In this case, I am setting it up to let people pipe to Haskell functions as well, forking off a process that works with pipes to handle them. I know how all these things work in Unix, in C, in Python, etc. I have no idea how all of this will interact if I were to use forkOS. It is not clear to me what the semantics of forkProcess, executeFile, signal handling, etc. are under a Haskell thread instead of a forked process. This is, as far as I can tell, completely undocumented in System.Posix.* and the subject of differing advice on the WWW. But let me add a voice to keeping the non-threaded RTS around. I have learned the hard way that the threaded RTS is ported only to a very few platforms, a distinct minority of the platforms that Debian supports, for instance. (Just like ghci). Whereas the non-threaded RTS is supported much more broadly (such as Alpha support). My own program hpodder has failed to build in Debian on many platforms because I didn't realize this going in. Not only that, but it is apparent that the threaded RTS is simply inappropriate when a person is trying to do anything remotely low-level on the system. I would hate to have to become a Haskell refugee, going back to Python, because Haskell I/O has become incompatible with fork(). I do not find a language to be useful, in general, unless it lets me fork and exec when I have to. -- John _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
