anchor.diff:  { stdenv, lib, fetchurl, file, openssl, mlton
  -, mysql, postgresql, sqlite
  +, mysql, postgresql, sqlite, gcc
   }:
   
   stdenv.mkDerivation rec {
  
positive.code:   configureFlags = "--with-openssl=${openssl.dev}";
  
    preConfigure = ''
      export PGHEADER="${postgresql}/include/libpq-fe.h";
      export MSHEADER="${lib.getDev mysql.client}/include/mysql/mysql.h";
      export SQHEADER="${sqlite.dev}/include/sqlite3.h";
  
      export CCARGS="-I$out/include \
                     -L${lib.getLib mysql.client}/lib/mysql \
                     -L${postgresql.lib}/lib \
                     -L${sqlite.out}/lib";
    '';
  
negative.code:     description = "Advanced purely-functional web programming language";
      homepage    = "http://www.impredicative.com/ur/";
      license     = stdenv.lib.licenses.bsd3;
      platforms   = stdenv.lib.platforms.linux ++ stdenv.lib.platforms.darwin;
      maintainers = [ stdenv.lib.maintainers.thoughtpolice stdenv.lib.maintainers.sheganinans ];
    };
  }
  