There are several facets that may be similarities. In both:
- First think about the overall story, the design. You know in your head the jist of what you want to do, but not all the little details.
- When you sit down to actually put the ideas down on paper, you often can just let your ideas flow out, as if you're in the zone... I imagine the great composers worked this way. The details fill themselves in as you go.
- It's only partly a science. There are virtually an infinite number of ways to do anything in software, and the same thing in music. Each person has their own signature.
- The finished product can be breathtakingly beautiful to the experienced eye, or it can be off-key and disjointed.
- The product (sheets of music or computer code) can't play or execute itself. It needs a musician or computer to perform it.
Often I've thought about these similarities as I engineer software, and I'd be interested to know if anyone else has thought the same thing.