[Haskell-cafe] Haskell not ready for Foo [was: Re: Hypothetical
Haskell job in New York]
manlio_perillo at libero.it
Thu Jan 15 13:31:41 EST 2009
John Goerzen ha scritto:
>> Python has pure interfaces to all the major databases. While it's true
>> there are no "native" GUI libraries, there are pure Python libraries for
>> just about everything else. Haskell is not yet to this point.
> By "pure" do you mean "containing python code only"? I'm looking
> through a few, and:
> PostgreSQL - psycopg - C
> PostgreSQL - pgsql - C
> PostgreSQL - pygresql - C
> MySQL - mysqldb - C
> MS SQL Server - pymssql - C
> And any interface that uses ODBC will, by necessity, be calling to C,
> because ODBC is defined as a C API and not a network protocol.
> Where are all these pure-Python drivers?
Time ago, I implemented a client for the network protocol used by
it covers almost all the protocol features (only extended queries are
It is implemented using Twisted.
I would like to reimplement it in Haskell, sometime in the future.
I tried to implement the MySQL network protocol, too, but it is a
*mess*, so I gave up (and, at that time, there were strange claims about
It is also possible to support MSSQL and Sybase, implementing a client
for the TDS (Tabular Data Stream) protocol.
TDS, too, is a mess (well, if you compare it with the PostgreSQL
protocol), and last time I studied it, the freeTDS project only had a
reversed engineered protocol documentation; now Microsoft has made the
TDS variant used my MSSQL public:
So, in theory, it should not really be a problem to implement native and
robust support for PostgreSQL, MySQL, MSSQL and Sybase.
One benefit of these implementation would be builtin support to
For PostgreSQL, a native implementation can be useful to listen notifies.
 the libpq API *has* support for async API, but it is not
complete (and well tested like sync API, IMHO).
As an example there is no support for async function call, although
"The Function Call sub-protocol is a legacy feature that is
probably best avoided in new code. Similar results can be accomplished
by setting up a prepared statement that does SELECT function($1, ...).
The Function Call cycle can then be replaced with Bind/Execute."
P.S.: the PostgreSQL protocol is really well designed
Regards Manlio Perillo
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