(Wow, it looks like my message has generated quite a bit of traffic!
Thanks, guys!)
On 12/11/06, Taral [EMAIL PROTECTED] wrote:
The magic commands are:
runhaskell Setup.lhs configure
runhaskell Setup.lhs build
runhaskell Setup.lhs install
Excellent! Now I'm getting somewhere. I even found the sample code in
the takusen documentation.
I'm trying to modify the sample code to work with a local database I
have, and I'm getting some type errors which mean nothing much to me.
The code I have, stored in a file called db.hs and run via runhaskell
db.hs is:
import Control.Monad.Trans
import Database.Oracle.Enumerator
import Database.Enumerator
query1Iteratee :: (Monad m) = String - IterAct m [String]
query1Iteratee a accum = result' (a:accum)
main :: IO ()
main = do
withSession (connect USER PASSWORD DB) $ do
-- simple query, returning reversed list of rows.
r - doQuery (sql select username from all_users) query1Iteratee []
liftIO $ putStrLn $ show r
The error I'm getting is
db.hs:10:64:
Couldn't match expected type `forall mark. DBM mark Session a'
against inferred type `a1 b'
In the second argument of `($)', namely
`do r - doQuery
(sql select username from all_users) query1Iteratee []
liftIO $ (putStrLn $ (show r))'
In the expression:
(withSession (connect USER PASSWORD DB))
$ (do r - doQuery
(sql select username from all_users) query1Iteratee []
liftIO $ (putStrLn $ (show r)))
In the expression:
do (withSession (connect USER PASSWORD DB))
$ (do r - doQuery
(sql select username from all_users) query1Iteratee []
liftIO $ (putStrLn $ (show r)))
I'm not sure what might be wrong here - or even, for that matter, how
to diagnose the problem. To complicate the matter, it's possible that
I'm getting a database connection error which I've not got code in to
report. (I've no easy way to test that the database connection from
Haskell is working, or rather *this* is the easy way :-))
Can anyone offer any pointers? (I take the suggestions about asking on
IRC, but I can't get at IRC from here due to firewall issues, so I'll
have to stick to email).
Paul.
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