Ccing cabal-dev.
On Aug 17, 2011 9:12 AM, "Rogan Creswick" <cresw...@gmail.com> wrote: > > On Wed, Aug 17, 2011 at 6:29 AM, Gang <yugang...@gmail.com> wrote: > > > > sorry to bother > > > > Not in the least! > > I was trying to figure out what problem you were encountering, and I > learned a lot. I never did recreate your problem, but in the process > I ran into a whole host of other annoyances and strange situations > relating to slightly broken cabal files and cabal build intricacies > that confound our existing tools. > > I don't mean to pick on encoding or HaXml - I've seen the same kinds > of issues in many, many Haskell packages (including most of the > packages I've written myself) these are just the ones I ran into > today. (and I am quite serious when I say that writing a good Setup.hs > is very, very, difficult). My objective is just to motivate a minor > change to cabal that would help to make this easier. > > On to the build problems: > > encoding-0.6.6 uses it's own source during the build process! It > actually has to be partially compiled before the build tool can build > encoding (!). I'm *amazed* that this actually works at all > (impressed, too), and indeed, it doesn't work with cabal-dev, which is > unfortunate: cabal-dev would have identified one of the dependency > issues in HaXml 1.19 (pretty is an undocumented dependency, although I > am unsure if that was true at the time 1.19 and encoding-0.6.6 were > released. I haven't tracked the pretty dependency down to the exact > source - it could be a transitive dep introduced by a recent version > of something HaXml 1.19 needs. Per my subject line - this is > amazingly difficult - keep in mind that we're not talking about > building *packages*, this is just to build the *build tool*, and none > of this is documented. How long before it is effectively impossible > to recreate the circumstances that result in a successful > encoding-0.6.6 build?). > > cabal-dev can't build encoding-0.6.6 because the encoding source that > is referenced from encoding's Setup.hs depends on (at least) HaXml >= > 1.19 && < 1.22.5; this is OK with cabal, since cabal-install installs > a necessary HaXml into your user package db prior to building > encoding's Setup.hs (modulo the missing upper version bound). > Therefore HaXml "just happens" to be visible when cabal builds > Setup.hs -- a build step that cabal-dev isn't capable of controlling > (and probably never will be -- we could intercept system calls, but > that's difficult when only supporting one OS, much less three). > > You can, of course, manually install HaXml to your local package db > and then cabal-dev install encodings, but that's somewhat of a hack > (and you'll find that the current HaXml won't work for the current > encodings release, as Gang Yu did). > > Adding a section to the cabal file that specifies build dependencies > for Setup.hs would make some very important parts of this process > obvious - and it would *greatly* assist in debugging failing builds, > not to mention allowing us to make use of the extensive libraries on > hackage to write more expressive build systems. (We could actually > use openshake in Setup.hs, once it's released, for example!) > > I've floated the idea past a number of Haskell programmers with > positive responses, and there is a GSOC ticket that provides some more > details (the project was not selected - no students proposed to work > on it): > > http://hackage.haskell.org/trac/summer-of-code/ticket/1602 > > --Rogan > > > Regards > > Gang > > On 08/17/2011 04:59 PM, Gang Yu wrote: > > > > hi, cafe: > > > > I go through to the encoding package installation problem again. > > > > cabal install encoding > > Resolving dependencies... > > /tmp/encoding-0.6.68093/encoding-0.6.6/dist/setup/setup: 4: Syntax error: > > ";" unexpected > > > > when I have a check on the this issue, I get: > > > > file > > ~/.cabal/packages/ hackage.haskell.org/encoding/0.6.6/encoding-0.6.6/dist/setup/setup > > /home/gang/.cabal/packages/ hackage.haskell.org/encoding/0.6.6/encoding-0.6.6/dist/setup/setup: > > ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked > > (uses shared libs), for GNU/Linux 2.6.27, not stripped > > > > My machine is: > > > > gang@gang-laptop:~$ uname -a > > Linux gang-laptop 2.6.38-8-generic #42-Ubuntu SMP Mon Apr 11 03:31:50 UTC > > 2011 i686 i686 i386 GNU/Linux > > > > is this related? How can I manually install the package from scratch? Any > > helps or directs will be appreciated > > > > Thanks > > Gang > > > > > > _______________________________________________ > > Haskell-Cafe mailing list > > haskell-c...@haskell.org > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > > > > _______________________________________________ > Haskell-Cafe mailing list > haskell-c...@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe
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