Instead of relying on Lua for our profile needs I would like to change the interface of libosrm_extract to:

Extractor::Run(const Profile& profile)

class Profile
{
    virtual ~Profile() = default;

    virtual ExtractionWay processWay(const osmium::Way&) = 0;
    virtual ExtractionNode processNode(const osmium::Node&) = 0;
    virtual double processSegment(const Segment&) = 0;
}

This abstract over calling lua directly. osrm-extract can implement a Profile that uses all the current scripting code contained in libosrm_extract to be backward compatible in the meantime.

Long term goal is to drop Lua as a dependency. Profiles will be moved to the node-osrm side and will be implemented in JS.