[web-devel] [Haskell-cafe] [ANN] mysql-simple - your go-to package for talking to MySQL

Bryan O'Sullivan bos at serpentine.com
Tue Jun 21 18:40:41 CEST 2011

On Tue, Jun 21, 2011 at 4:45 AM, David Virebayre <dav.vire+haskell at gmail.com
> wrote:

> I had trouble accessing the documentation : the last versions on
> hackage have a build failure, so the doc isn't available.

I don't understand why that build failure occurs. You can always build
documentation for a package locally using "cabal haddock".

> The very first example didn't work for me :

Oops, thanks for mentioning that. I've fixed the documentation and made the
information about type inference a little clearer.

Indeed, the documentation shows that convertError takes 3 parameters,

and I gave, as per the example, only 2.
> But I'm not sure what to write for the 3rd parameter, the
> documentation doesn't help me here.

Thanks for spotting the omission, I've clarified that. The Int parameter
indicates the number of columns expected for conversion.

> I'm not sure if that means Database.MySQL supports calling stored
> procedures that return a result set or not. I suspect not.

The mysql-simple package currently doesn't support stored procedures or
multi-statement queries. Each of these can return multiple result sets. It
would be necessary to add new functions to the API to support them, as of
course each result set could have a different shape.
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