Re: GHC 7.4.2 on Ubuntu Trusty
I wrote: >> This thread makes it clear what a mess >> we have inherited from the days when GHC was primarily a >> research compiler. Let's face it - GHC is now also a serious >> production compiler, and this urgently needs to be cleaned up. hvr wrote: > Are you referring to the GMP dependency or something else? > ...I'm not sure what can be done differently here. Agreed. No, not any one of those many little details. I mean the general extreme difficulty of getting almost any version of GHC working on almost any platform, unless the two were released within a fairly short time of each other. Well, that is, not counting your wonderful ppa for Ubuntu. That is fantastic - but the dire need for it is evidence for the severity of the problem. How about this: Currently, every GHC source distribution requires no later than its own version of GHC for bootstrapping. Going backwards, that chops up the sequence of GHC versions into tiny incompatible pieces - there is no way to start with a working GHC and work backwards to an older version by compiling successively older GHC sources. If instead each GHC could be compiled using at least one subsequent version, the chain would not be broken. I.e., always provide a compatibility flag or some other reasonably simple mechanism that would enable the current GHC to compile the source code of at least the last previous released version. I realize that this might be disruptive to GHC devs, because as a compiler with a research heritage, GHC experiments with its own new features on its own source code. But as a compiler that is used commercially, some general kind of backward portability is critically important. The other direction is equally problematic. Although GHC does support bootstrapping itself from a few previous releases, porting GHC to a new platform has become harder and harder as GHC becomes more complex. I think this could become a threat to the viability of GHC - technology is always changing. As a commercial developer, I am always plagued by nagging worry about GHC portability, forward and backward. Will we always be able in the future to support code we release, or will it die someday because there will no longer exist a GHC able to compile it? Will our whole technology die someday just because we can't get GHC working on a platform we need to support? Thanks, Yitz ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: GHC 7.4.2 on Ubuntu Trusty
Excerpts from Yitzchak Gale's message of 2014-10-28 13:58:08 -0700: > How about this: Currently, every GHC source distribution > requires no later than its own version of GHC for bootstrapping. > Going backwards, that chops up the sequence of GHC versions > into tiny incompatible pieces - there is no way to start with a > working GHC and work backwards to an older version by compiling > successively older GHC sources. > > If instead each GHC could be compiled using at least one > subsequent version, the chain would not be broken. I.e., > always provide a compatibility flag or some other reasonably > simple mechanism that would enable the current GHC to > compile the source code of at least the last previous released > version. Here is an alternate proposal: when we make a new major version release, we should also make a minor version release of the previous series, which is prepped so that it can compile from the new major version. If it is the case that one version of the compiler can compile any other version in the same series, this would be sufficient to go backwards. Concretely, the action plan is very simple too: take 7.6 and apply as many patches as is necessary to make it compile from 7.8, and cut a release with those patches. Edward ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Recursion on TypeNats
Hello, actually type-level integers are easier to work with than type-level naturals (e.g., one can cancel things by subtracting at will). I agree that ideally we want to have both integers and naturals (probably as separate kinds). I just don't know what notation to use to distinguish the two. -Iavor On Mon, Oct 27, 2014 at 2:13 PM, Barney Hilken wrote: > Ok, I've created a ticket https://ghc.haskell.org/trac/ghc/ticket/9731 > > Unfortunately I don't know enough about ghc internals to try implementing > it. > > ___ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Thread behavior in 7.8.3
I have a general question about thread behavior in 7.8.3 vs 7.6.X I moved from 7.6 to 7.8 and my application behaves very differently. I have three threads, an application thread that plots data with wxhaskell or sends it over a network (depends on settings), a thread doing usb bulk writes, and a thread doing usb bulk reads. Data is moved around with TChan, and TVar is used for coordination. When the application was compiled with 7.6, my stream of usb traffic was smooth. With 7.8, there are lots of delays where nothing seems to be running. These delays are up to 40ms, whereas with 7.6 delays were a 1ms or so. When I add -N2 or -N4, the 7.8 program runs fine. But on 7.6 it runs fine without with -N2/4. The program is compiled -O2 with profiling. The -N2/4 version uses more memory, but in both cases with 7.8 and with 7.6 there is no space leak. I tired to compile and use -ls so I could take a look with threadscope, but the application hangs and writes no data to the file. The CPU fans run wild like it is in an infinite loop. It at least pops an unpainted wxhaskell window, so it got partially running. One of my libraries uses option -fsimpl-tick-factor=200 to get around the compiler. What do I need to know about changes to threading and event logging between 7.6 and 7.8? Is there some general documentation somewhere that might help? I am on Ubuntu 14.04 LTS. I downloaded the 7.8 tool chain tar ball and installed myself, after removing 7.6 with apt-get. Any hints appreciated. Mike ___ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
