Great feedbacks Araq and monster . I don't want this topic to be about my motivation specifically but everyone's experience, also this kind of topics happens often in Quora and Reddit so maybe we could top Google search and get some new blood this way .
Now I do sports, several hours per week (more addicted to it than programming actually) and thankfully for Arraymancer, plenty of data scientists would love to try and benchmark the hell out of it once a MVP is done (i.e. recognizing images with 90%+ accuracy). So for the next people: As monster is asking, what keeps you motivated or make you most happy in an open-source project (or inversely)
