Hallo list, I don't quite get how ($!) works. I have this function:
dbCreateIndices con dtn dof = do let dummy = newDbItem let query = "SELECT id FROM " ++ (dtn dummy) ++ " ORDER BY " ++ (dof dummy) ids <- liftM (map fromSql . concat ) $! quickQuery con query [] return $ IntMap.fromList $ zip ids [0..] quickQuery returns a lazy list of results, and I expected ($!) to make it strict. But my program crashes if I use it this way. But, if I add a print to the function: dbCreateIndices con dtn dof = do let dummy = newDbItem let query = "SELECT id FROM " ++ (dtn dummy) ++ " ORDER BY " ++ (dof dummy) ids <- liftM (map fromSql . concat ) $! quickQuery con query [] print ids return $ IntMap.fromList $ zip ids [0..] print makes the ids list strict and all is well. How is the correct way to use ($!) ? Cheers, -- -alex http://www.ventonegro.org/ _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe