On Tue, 2008-11-18 at 01:48 -0800, Jason Dusek wrote:
I'd like to be able to do something like:
if (template-haskell < 2.3) cpp-options: -D TH_THE_YOUNGER else cpp-options: -D TH_THE_ELDER
I guess this kind of thing is not possible at present?
It is possible, in two different ways. The easiest way is that if you're using Cabal-1.6 then it provides cpp macros to test the version number of packages you're using. #if MIN_VERSION_template_haskell(2,3,0) ... #elseif ... #endif The alternative that works back to Cabal-1.2 is to use: flag newer-th ... if flag(newer-th) build-depends: template-haskell >= 2.3 cpp-options: -D TH_THE_ELDER else build-depends: template-haskell < 2.3 cpp-options: -D TH_THE_YOUNGER See also ticket http://hackage.haskell.org/trac/hackage/ticket/209 for a proposal to add syntactic sugar similar to the syntax you first suggested. Duncan