[atonse]

My take with the analogy here is that you're still playing the guitar to make songs (an end product), instead of just learning how to pluck strings for the sake of plucking strings and testing how different strings of different materials feel for the heck of it.

[ebbv]

But that latter thing is still something guitarists do. You might throw some new strings on and noodle around for a day with no particular purpose in mind.

Likewise it's fine to write code with no bigger goal other than to play with a library or a language.