[Haskell-cafe] coding standard question

[Daniel Fischer]

Am Freitag 26 Juni 2009 11:30:32 schrieb david48:
> On Thu, Jun 25, 2009 at 3:27 AM, wren ng thornton<wren at freegeek.org> wrote:
> > If certain warnings truly are spurious and unavoidable, then it's best to
> > document this explicitly in the code by pragmas to disable the relevant
> > warnings. This way the spurious nature of the warning is documented (for
> > future maintainers, including yourself) and the distracting output of the
> > compiler is removed as well. Unfortunately, GHC only gives whole-file
> > scope for disabling warnings, but that could be fixed with enough work.
>
> Hello all,
> Forgive me if I'm a bit out of topic, but following this thread, I
> decided to add -Wall -Werror for a program I'm working on.
> I've spend a bit of time correcting quite a lot of warnings, most of
> them being about missing type signatures. I've corrected them all, but
> there remains one that I can't :  ghc refuses the type signature it
> suggests me.
>
> Anyone has any idea ?
>
> =====================================
> david at pcdavid2:~/projets/haskell/caimonitor$ ./g
> [3 of 4] Compiling Bdd              ( Bdd.hs, Bdd.o )
>
> Bdd.hs:27:0:
>     Warning: Definition but no type signature for `connecter'
>              Inferred type: connecter :: IO
>
> HDBC-mysql-0.6:Database.HDBC.MySQL.Connection.Connection
>
> <no location info>:
> Failing due to -Werror.
> =====================================
>
> Here's part of the code : without -Werror, the code compiles and works
> fine.
>
> ======================================
> module Bdd where
>
> import Database.HDBC
> import Database.HDBC.MySQL
> import Text.Printf
> import Messages
>
> mysqlInfo :: MySQLConnectInfo
> mysqlInfo = defaultMySQLConnectInfo { mysqlHost ="xxx.xxx.xxx.xxx"
>                                     , mysqlUser = "xxxxxxxx"
>                                     , mysqlPassword = "xxxxxxxx"
>                                     , mysqlDatabase = "xxxxxx"
>                                     , mysqlPort = 0
>                                     , mysqlUnixSocket =""
>                                     }
>
> --connecter :: IO Database.HDBC.MySQL.Connection.Connection

Looks like you must also 
import Database.HDBC.MySQL.Connection

or, if the type Connection is exported from one of the imported modules, use it unqualifed 
or qualified with that module name.

> connecter        = connectMySQL mysqlInfo
> ...
> ...
> ...
> ======================================
>
> Thanks,
>
> David