[Haskell-beginners] Getting the Takusen example code to compile
-failed import problem
djeinbrum at yahoo.co.uk
Thu Aug 6 14:21:19 EDT 2009
> > I have Takusen 0.8.5 installed and I'm trying to build
> > code found at
> > http://darcs.haskell.org/takusen/doc/html/Database-Enumerator.
> html using ghc 6.10.3. This always fails with the
> > Could not find module `Database.Oracle.Enumerator'
> > The analogous errors are encountered if I substitute
> > with Sqlite, Postgresql or ODBC. Any ideas how
> to resolve this?
OK, this now compiles thanks to (a) hacking Setup.hs to refer to odbc_config rather than odbcconf and (b) unregistering the user packages with ghc-pkg --user unregister Takusen.
However, if I then create a table in MySQL with:
create table dummy (id int primary key);
and then use a reduced form of the example code:
query1Iteratee :: (Monad m) => Int -> String -> Double -> IterAct m [(Int, String, Double)]
query1Iteratee a b c accum = result' ((a, b, c):accum)
main :: IO ()
main = do
withSession (connect "DSN=test") ( do
-- simple query, returning reversed list of rows.
r <- doQuery (sql "select id from dummy") query1Iteratee 
then I get the error:
fromUTF8Ptr: zero byte found in string as position 8
Is there any thing wrong with the above code?
Also, what does liftIO actually do? Its documentation at http://cvs.haskell.org/Hugs/pages/libraries/mtl/Control-Monad-Trans.html does not actually say! The link at the top of that page is dead as well.
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