[Haskell-cafe] databases in Haskell & type-safety

[Austin Seipp]

Excerpts from Gour's message of Sat Jan 03 03:48:44 -0600 2009:
> Hi!
> 
> I'd like to use sqlite3 as application storage in my haskell project...
> 
> Browsing the available database options in Haskell it seems that:
> 
> a) HSQL is dead (hackage reports build-failure with 6.8 & 6.10)
> 
> b) haskelldb is also not in a good shape - build fails with 6.8 & 6.10
> 
> For Haskell-newbie as myself, it looks that haskelldb is the one which
> provide(ed)s the most secure API (I was reading draft paper about
> MetaHDBC but, apparently, the type inference support in open-source
> databases is poor and that's why, according to the author "This is
> unfortunately as it makes MetaHDBC a lot less valuable." 
> 
> What remains is:
> 
> c) Takusen which is also not up-to-date (it fails with 6.10) and
> 
> d) HDBC and sqlite bindings which are the only packages which build with
> 6.10.

Have you tried the simple sqlite3 bindings available?
http://hackage.haskell.org/cgi-bin/hackage-scripts/package/sqlite

> I'm not familiar with Takusen which says: "Takusen's unique selling
> point is safety and efficiency..." and I would appreciate if someone
> could shed some more light to its 'safety' and the present status?

Takusen is based on the (unique) concept of a left-fold
enumerator. Having a left-fold interface guarantees timely (nearly
perfect, really) deallocation of resources while still having the
benefits of a 'lazy' stream. This interface has (as shown by Oleg and
others) proven to be very efficient in a number of cases as well as
favorable for many. The idea is very novel, and truly worth exploring
if you ask me.

For more information about left-fold enumerators and takusen, see here:

http://okmij.org/ftp/papers/LL3-collections-enumerators.txt
http://okmij.org/ftp/Haskell/fold-stream.lhs
http://okmij.org/ftp/Haskell/misc.html#takusen

NB: I have *just* (about 5 minutes ago) sent in a patch for takusen
to get it to build on GHC 6.10.1 to Oleg. Hopefully an updated version
will appear on hackage in the next few days.

Austin