anchor.diff:  
     qcmm = import ../development/compilers/qcmm {
       lua   = lua4;
  -    ocaml = ocaml_alts.v_3_08_0;
  +    ocaml = builtins.getAttr "3.08.0" ocaml_alts;
       inherit fetchurl stdenv mk noweb groff;
     };
   
  
positive.code: 
    pyrexFun = lib.sumArgs (import ../development/interpreters/pyrex) {
    	inherit fetchurl stdenv stringsWithDeps lib builderDefs;
  	python = python_alts.v_2_5;
    };
  
    pyrex = pyrexFun {
  
negative.code: 
    pythonmagick = import ../applications/graphics/PythonMagick {
      inherit fetchurl stdenv pkgconfig imagemagick boost;
      python = builtins.getAttr "2.5" python_alts;
    };
  
    ratpoison = import ../applications/window-managers/ratpoison {
  