[Haskell-cafe] ANN: HDBC v2.0 now available

[Valentyn Kamyshenko]

Hello John,

I'm trying to install the new version of HDBC on my Mac (ghc version  
is 6.10.1), and get the following error:

# cabal upgrade --global
Resolving dependencies...
'HDBC-2.0.0' is cached.
Configuring HDBC-2.0.0...
Preprocessing library HDBC-2.0.0...
Preprocessing executables for HDBC-2.0.0...
Building HDBC-2.0.0...
[1 of 7] Compiling Database.HDBC.SqlValue ( Database/HDBC/SqlValue.hs,  
dist/build/Database/HDBC/SqlValue.o )
[2 of 7] Compiling Database.HDBC.ColTypes ( Database/HDBC/ColTypes.hs,  
dist/build/Database/HDBC/ColTypes.o )
[3 of 7] Compiling Database.HDBC.Statement ( Database/HDBC/ 
Statement.hs, dist/build/Database/HDBC/Statement.o )

Database/HDBC/Statement.hs:113:9:
     Type constructor `Exception' used as a class
     In the instance declaration for `Exception SqlError'
cabal: Error: some packages failed to install:
HDBC-2.0.0 failed during the building phase. The exception was:
exit: ExitFailure 1

any suggestions?

Thanks you,

   Valentyn.

On Jan 30, 2009, at 1:28 PM, John Goerzen wrote:

> Hi everyone,
>
> I'm pleased to announce that HDBC v2.0 is now available.
> Simultaneously, HDBC-sqlite3, HDBC-postgresql, and HDBC-odbc v2.0 have
> also been uploaded.  All may be found from Hackage, or at
> software.complete.org.
>
> A guide to new features and migration can be found at:
>
>  http://software.complete.org/software/wiki/hdbc/NewIn20
>
> A partial summary of it follows:
>
> New Features:
>
>     * Pervasive Unicode support now part of the HDBC API and  
> implemented
>       by all backend drivers. Based on utf8-string and conversions
>       between UTF-8 ByteStrings and Haskell Strings.
>
>     * Full support for GHC 6.10 is new. Full support for GHC 6.8 is
>       maintained.
>
>     * Native support for the new exception handling in GHC 6.10,  
> with CPP
>       conditional compilation to continue supporting the old-style
>       exceptions for users of GHC 6.8 or Hugs.
>
>     * HDBC now has direct support for marshalling virtually all of the
>       Data.Time.* types to and from SQL database date/time types.  
> toSql
>       and fromSql/safeFromSql now support conversions between  
> Data.Time.*
>       types and SqlValue. Conversions between System.Time.* types were
>       present from the beginning and will remain. Automatic  
> conversions
>       are, of course, contingent on support in database engines and  
> HDBC
>       database backend drivers and may not be possible with all
>       databases.
>
>     * Major expansion of SqlValue to be able to carry date/time data
>       to/from databases in terms of Data.Time.* types.
>
>          + The old SqlTimeDiff and SqlEpochTime types continue to be
>            present, but are deprecated and will be removed in a  
> future.
>            toSql no longer converts anything to them. The  
> System.Time.*
>            types are converted to the new Data.Time-based SqlValues.  
> It
>            should be exceptionally rare that any user code would use
>            these types directly, but they are being retained in this
>            version out of an abundance of caution.
>
>     * Replace fromSql with safeFromSql, which returns Left on  
> impossible
>       conversions instead of raising an exception.
>
>          + Wrote a new fromSql that behaves just like the old one,  
> but is
>            implemented in terms of safeFromSql. It converts the
>            safeFromSql errors to exceptions.
>
>          + The new structure made it possible to greatly enhance many
>            error messages throughout the conversion process instances.
>
>          + Removed SqlType typeclass. Re-implemented SqlValue  
> conversions
>            in terms of the generic infrastructure in the convertible
>            package. Simplified code significantly due to this.
>
>     * Lots of additional docs.
>
>     * New skeleton test suite for HDBC itself (to be expanded upon
>       later).
>
> Richer Date and Time Support
>
>   HDBC 1.x had only two ways of getting dates and times between  
> Haskell
>   and a database: an epoch (an Integer representing the number of  
> seconds
>   since midnight Jan 1 1970 UTC) and an Integer representing a  
> TimeDiff
>   (a count of elapsed time). While this approach could represent a
>   precise instant in time, it was not always the most helpful. Most
>   notably, you might sometimes want to load date information without
>   time, time without date, or record what timezone the time was  
> measured
>   within. HDBC can now convert all of these things with much greater
>   precision.
>
> Thanks to Phil Wise for adding the first Unicode support (to
> HDBC-postgresql originally) and to Alson Kemp for adding the first
> advanced date/time marshalling support (also to HDBC-postgresql
> originally).  The experience of adding these features to a single
> backend driver first made clear a good way to add them to HDBC API
> as a whole.
>
> -- John
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