# [Haskell-cafe] OpenVG: Linker errors with ghc --make, but not with ghci?

Peter Verswyvelen bugfact at gmail.com
Wed Mar 4 09:16:33 EST 2009

Thanks for the feedback.

Yes this is definitely a complex thing.

I succeeded in just the opposite: with a lot of hackery I got the FTGL
binding on Hackage to compile and correctly run. However, when using
it from GHCi it "compiles" correctly but fails to load the font and
hence crashes.

I'll try to look into the problem too, since I want to learn the FFI stuff.

I'm also thinking to wrap QuesoGLC since it seems to have a nicer API
then FTGL although I'm not sure it's worth the trouble

On Wed, Mar 4, 2009 at 12:25 PM, Stephen Tetley
<stephen.tetley at gmail.com> wrote:
> Hi Peter
>
> Yes this is definitely a problem with the OpenVG package.
>
> Although I wrote the package I don't know enough about the minutiae of
> Windows .dlls to sort this out directly (even though I did write most
> of the library on a Windows machine). I could try to and write a
> cabal+makefile build rather than a pure cabal one to follow the
> example of the OpenGL and GLUT libraries, though I don't know if that
> would work. With my current OpenGL and GLUT installation[1] on Windows
> I can only run GL programs from GHCi rather than compile them.
>
> Please let me know if you want me to try a cabal+makefile package,
> though the turnaround might not be quick.
>
> Best wishes
>
> Stephen
>
> [1] installed by following these instructions
> http://netsuperbrain.com/blog/posts/freeglut-windows-hopengl-hglut/
>
>
>
> 2009/3/4 Peter Verswyvelen <bugfact at gmail.com>:
>> I followed the instructions on how to build OpenVG on Windows. It works fine
>> when I run the examples using "GHCi -lopenvg32", but when compiling it with
>> "GHC --make -lopenvg32" I get a bunch of linker errors, like
>> C:\Program
>> undefined reference to `vgInterpolatePath'
>> C:\Program
>> undefined reference to `vgModifyPathCoords'
>> etc
>> However it does seem that the libopenvg32.a file contains all these
>> undefined references, and it is in the gcc-lib directory of GHC.
>> I'm a stuck. Any hints?
>> Thanks,
>> Peter
>>
>> _______________________________________________