On Tue, Jan 13, 2009 at 8:47 PM, Alex Ott
Hello
"SF" == Sigbjorn Finne writes: SF> Hi, a new release of the 'json' package is now available via hackage, SF> version 0.4.1
SF> http://hackage.haskell.org/cgi-bin/hackage-scripts/package/json
I tried to upgrade it via cabal on mac os x & linux (both use ghc 6.10.1) and it fails with
Building json-0.4.1...
Text/JSON/Generic.hs:33:7: Could not find module `Data.Generics': it was found in multiple packages: base-3.0.3.0 syb cabal: Error: some packages failed to install: json-0.4.1 failed during the building phase. The exception was: exit: ExitFailure 1
The standard solution for this is to add a cabal flag that controls wether to depend on base-4 or base-3: ------------------------------------------------------ flag small_base description: Choose the new smaller, split-up base package. Library if flag(small_base) Build-Depends: base == 4.*, syb CPP-Options: -DBASE_4 else Build-Depends: base == 3.* ------------------------------------------------------ And use some CPP in your modules like this: ------------------------------------------------------ {-# LANGUAGE CPP #-} #ifdef BASE_4 import Data.Data (Data) #else import Data.Generics (Data) #endif ------------------------------------------------------ See for example how I do it in http://code.haskell.org/Stream regards, Bas