Ask HN: How to Learn a Musical Instrument Like a Hacker? (specifically piano)

I want to learn to play the piano, as I currently have no artistic form of self-expression. However, I feel like learning so many computer-related skills has changed the way I learn (for the better, I think). So, to all you of that have also spent enough time persistently working at code that you are a relentless skill-learners, what's the best way to learn an instrument in a thorough, engaging, and efficient manner? I'm planning on learning the piano, but any general advice would be useful, and would help more people.