Re: [Haskell-cafe] Control.Exception base-3/base-4 woes

On Fri, Sep 11, 2009 at 10:42 AM, David Menendez wrote:

On Fri, Sep 11, 2009 at 11:26 AM, Neil Brown wrote:

...

Can anyone tell me how to fix this?  I don't think that changing to always use Control.Exception would fix this, because I need to give a different type for catch in base-3 to base-4, so there's still the incompatibility to be dealt with.

I'd try using a cabal flag to set a CPP flag.

E.g., from cabal

   Flag Base3        Description: Use Version 3 of Base        Default: False

   Library/Executable        if flag(Base3)            CPP-Options: -D _BASE_3_            Build-Depends: base >= 3 && < 4

       else            Build-Depends: base >= 4 && < 5

And then do,

   #if _BASE_3_    import qualified Control.Exception as C    #else    import qualified Control.OldException as C    #endif

I've had success with this. See: http://hackage.haskell.org/packages/archive/uuid/1.0.2/uuid.cabal Antoine