On Thu, 26 Jun 2008, Alistair Bayley wrote:
Yes, puzzling. I don't know why you need to say -lclntsh, because that's the point of all of this Setup shenanigans: to get things set up so that ghci works nicely.
That's why we have flags that expose/hide modules in the API: ghci has a custom linker, and this tries to link everything in the library, and of course this fails if you don't have the .ddl/.so installed for a particular backend. ghc uses gnu ld to link, and this does not try to link unused modules, so this works fine with the entire library API compiled.
Do you need to say -lclntsh when you use ghc to compile?
Ah, I see, I must run both GHCi and GHC with -package Takusen and everything is fine.
Next step is to fetch real data from the database. But now I encounter new problems. If I write a real 'select' statement I get at best:
Unexpected null in row 1, column 1. *** Exception: (unknown)
This looks like you are fetching a null value back with an iteratee that does not expect nulls. We use Maybe to specify that a column in the result-set can be null e.g.
iter :: Int -> Maybe Int -> Maybe String -> IterAct [(Int, Maybe Int, Maybe String)]
Indeed, using Maybe as type solves that problem.
and at worst:
50001752 *** glibc detected *** /usr/lib/ghc-6.8.2/ghc-6.8.2: free(): invalid pointer: 0x08d10065 *** ======= Backtrace: =========
If this continues, can you provide a test case for me?
I cannot reliably reproduce this. Sometimes it seems that the first run of 'main' succeeds, and the second one crashes in GHCi. So, many thanks for the help!