Software is definitely a craft(for some). It is also art, science, engineering and design. Software is even biology for some. It is whatever you wish to throw into it. Software is then also for me play, service, and factory work.

On where good libraries come from… I find that often a module, or package will come from an application.

After something needs to be used in more than one place, then it sometimes makes sense to make it available in one spot rather than copying it.

After I have made many similar types of programs, and slowly improve apon each of them, taking out the good parts, a good library can emerge. You remember making something before, so you grab it, and put it in a library.

However not first without much effort to make sure that the parts are well tested, and robust. After seeing flaws in them after use, you can take them and mold them into something better.

One really interesting place to look in software is at game development, and all of the people making ‘engines’. There’s lots of these people, that instead of working on games, want to make good engines. So they work, and work… and work, and work. Then someone comes along, and makes a game, then finishes another, and another. Soon enough they have finished four games before the engine builders have gotten their ‘clean’ API engine working.

Have fun!