On Samstag, 29. Dezember 2012, 18:25:45, Graham Klyne wrote:
A couple of problems with Network.URI have been brought to my attention, so I thought I'd have a go at seeing if I could fix them. It's been a while (years) since I used the Haskell toolchain in anger, so I'm a bit out of touch with how thinks are working now.
So far, I have:
1. Installed Haskell platform (64-bit version for MacOS). 2. Checked out the 'network' project from https://github.com/haskell/network 3. cabal install test-framework 4. cabal install test-framework-hunit 5. changed to the 'test' directory of the checked out 'network' project
Then when I try to run GHC, I get this error: <snip>
The problem seems to be with the following lines in URI.hs (starting at line 135): [[ # if MIN_VERSION_base(4,0,0) import Data.Data (Data) # else import Data.Generics (Data) # endif ]]
If I remove these lines, and just leave [[ import Data.Generics (Data) ]]
I can compile and run the test suite just fine: [[ Test Cases Total Passed 319 319 Failed 0 0 Total 319 319 ]]
I'm _guessing_ the problem here is something to do with "MIN_VERSION_base(4,0,0)" - not being familiar with the current build environment setup, I'm not sure where it is or should be defined, or what it is intended to mean.
The MIN_VERSION_package is a macro that cabal creates when building the package, that checks whether the available package version satisfies the minimum requirements. When hacking on a package without using cabal, you can a) remove the problematic macro b) define it in the file yourself c) pass -D"MIN_VERSION_base(x,y,z)=1" on the command line (I've tested option c only for C code, it might not work here, but afaik, gcc's preprocessor is used, so I think it will). Since you will probably compile more than once, a) or b) would be the preferable options. But you could also leave the macro as is and just $ cabal build the package. That needs one $ cabal configure before the first build, after that, a `cabal build` will only recompile changed modules (and what depends on them), so the compilation should be reasonably fast.
I did find these: * http://www.haskell.org/pipermail/haskell-cafe/2012-August/102787.html * http://stackoverflow.com/questions/8961413/zlib-build-error-with-ghc but they didn't help me.
It seems there's a fix that involves using __GLASGOW_HASKELL__ instead of MIN_VERSION_base(4,0,0), but I'm not sure exactly how that would play out - or indeed if that's the correct approach for a permanent fix.
In principle, the MIN_VERSION macro is the right thing, because it tests for the package version where things changed. For base, a suitable __GLASGOW_HASKELL__ condition is of course equivalent to a base-version check.