On Wed, Jul 7, 2010 at 9:46 PM, Jonathan Daugherty <drcyg...@gmail.com>wrote:
> > Anyway, the point remains, we need a single goto database library. > > > > Though the lack of response to this thread makes me think no one > > particularly thinks this is a problem. > > This is an interesting problem. For my part, I suspect the > proliferation of high-level database libraries is going to continue. > If you were to convince the present package maintainers to pitch in > and build a Grand Database Library, inevitably someone would come > along and build another one for whatever reason. Also, I don't think > the dust has settled on techniques for database access in Haskell in > any case, even for RDBMSs in particular. > > For what it's worth, I would be happy to get persistent[1] behind a Grand Database Library. Right now, the PostgreSQL backend[2] is built on HDBC while the SQLite backend[3] includes a variant of the direct-sqlite package[4]. Here's my two cents on why I didn't run with HDBC for both: * I wanted the SQLite backend to be the default backend that anyone could use, without library dependencies. It would be nice if HDBC-sqlite3 had an option to build against the sqlite3 amalgamation instead of system libraries. (In fact, it would be cool if that were the default, and system libraries the option.) * I'm not fond of the Convertible typeclass. In particular, it makes no distinction between conversions which are guaranteed to succeed (Int -> String) and conversions which might fail (String -> Int). As a result, the fromSql function can easily throw a runtime error. (For that matter, toSql could as well, but that is much less likely.) * I would like to be able to explicitly finalize statements. I believe I've gotten some exceptions in the past when trying to close a database connection because some statements were not finalized, but I can't remember the details right now. * I don't like that the lazy versions of functions are the default, and you have to add the ' for strict. It's too easy to make mistakes with the results of a lazy database query. I would even go so far as to recommend removing them entirely, but I think most people will not like that. Overall, I think HDBC is a great library, but I have no experience with the alternatives. The idea of breaking things into low-level C bindings and higher-level stuff on top is great. Michael [1] http://hackage.haskell.org/package/persistent [2] http://hackage.haskell.org/package/persistent-postgresql [3] http://hackage.haskell.org/package/persistent-sqlite [4] http://hackage.haskell.org/package/direct-sqlite
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