[Haskell-cafe] Re: SOE/GLFW compilation problems

[apfelmus]

Joel Stanley wrote:
> I've recently been able to get the SOE/GLFW code up and running from
> 
>     http://haskell.org/soe/software1.htm
> 
> and things are working well under GHCi under Mac OS X.
> 
> However, when attempting to compile a simple graphics script using ghc, I'm
> getting some unexpected link errors:
> 
> $ ghc -o mygfx mygfx.hs -iSOE/src
> compilation IS NOT required
> /usr/bin/ld: Undefined symbols:
> _SOE_Blue_closure
> _SOE_Red_closure
> _SOE_closeWindow_closure
> _SOE_drawInWindow_closure
> _SOE_ellipse_closure
> _SOE_getKey_closure
> _SOE_openWindow_closure
> _SOE_polyline_closure
> _SOE_runGraphics_closure
> _SOE_withColor_closure
> collect2: ld returned 1 exit status
> 
> I'm quite new to Haskell, so I'm not sure if there was something special I
> had to do in order to get the code for the closures generated by ghc.

You can just use --make and ghc will figure things out automatically

   ghc --make mygfx.hs -o mygfx -iSOE/src

(mygfx.hs must be the  Main  module for that to work, though)

If you want to do it by hand/Makefile, you need to compile ("ghc -c") 
the SOE code first and then link the resulting object files ("ghc -o 
mygfx SOE.o Draw.o ..."). See

    http://www.haskell.org/ghc/docs/latest/html/users_guide/
    separate-compilation.html#using-make

for an example Makefile that shows how it's done.

Regards,
apfelmus