[Haskell-cafe] Building/installing haskelldb and friends with ghc 6.10.1

Laurent Giroud ml at niaow.com
Sat Dec 6 17:32:11 EST 2008

Hi everyone,

I have been trying to install haskelldb in the last few days and  
encountered a number of hurdles which raised a few questions and for  
which I'd appreciate some insight and advice. Note that I am posting  
here because they are not specifically haskelldb related.

I am using Cabal to install haskelldb, haskelldb-hsql, haskelldb-hsql- 
mysql (and others) and discovered that the packages available on  
hackage do not build properly with ghc 6.10.1. The typical error being  
of the following kind:

     Could not find module `System.Time':
       it is a member of package old-time-, which is hidden

These ones are relatively easy to fix by finding the locally  
cached .tar.gz and modifying the .cabal file to include the  
corresponding packages (there were several of them which were  
discovered in successive attempts).
But I finally stumbled on hsql-mysql due to it apparently not being  
actively maintained anymore (this seemingly simple conclusion actually  
required quite a lot of research).
I read on haskell-cafe that Frederik Eaton had been apparently fixing  
these problems but could find nowhere a version exhibiting the will to  
compile gracefully, a darcs repository at http://code.haskell.org/ 
HSQL/ apparently containing patches from him also proved reluctant to  
build, although for different reasons. I wasn't courageous enough to  
pursue and try to fix them at that point of the adventure.

Other searches in haskell cafe lead me to people advising to use HDBC  
instead, after which I contemplated suicide for a few seconds before  
coming back to my senses and cabal-installing haskelldb-hdbc which  
quickly led me to error messages of the exact same kind mentioned above.
Strangely enough, hdbc 1.1.5 itself installs quite fine using Cabal,  
however, haskell-hdbc insists on depending on version 1.0.1. I haven't  
been able so far to find what configuration file to modify in order  
for it to try to build with the latest Cabalized version (I admit I  
didn't search much).

I then discovered this page http://www.haskell.org/haskellwiki/Upgrading_packages 
  which hints that some of the existing packages in Hackage need "a  
bit" of work to be usable with ghc 6.10.1 as well as ghc 6.8.x  
HSQL and haskelldb-HDBC seem indeed to be in the list of packages  
which would require some effort in order to be usable with the latest  
ghc versions (can't remember where I read that though).

Pursuing any further would seem to require to delve deeper in the  
intricacies of the Cabal system and fix either HSQL or HaskellDB-HDBC.  
Since I really want to use HaskellDB I'll probably try these avenues,  
but I would appreciate comments at this point from persons  
knowledgeable in the evocated areas:

Are the databases interface for haskelldb still officially maintained  
and where is this information available ?

Is the information that this and that package are compatible (or not)  
with ghc 6.8.x or 6.10.1 available somewhere without compiling first  
hand the packages ? It would be immensely valuable to the haskell  
newcomer to have the incompatible packages signaled on http://hackage.haskell.org/packages/archive/pkg-list.html 
  for example.

What would you recommend at this point : fix hsql, or haskelldb-hdbc  
so it uses 1.1.5 instead of 1.1, try an alternative to haskelldb (are  
there any ?) ?

Thanks in advance for your comments and advices.

Best regards,
Laurent Giroud
ml at niaow.com

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