A lot of my writing is musical, not only in the obvious form of songwriting, but also through songs embedded in prose fiction. (Copperhead Bill, anyone?)
I believe prose, poetry, and music constitute a continuum. We may not have a staff defining music for our prose, but italics can be used to imply melody.
And punctuation can lay down the beat.
Also, despite conventions that make song lyrics easily recognizable as such — for example, repeated refrains — many song lyrics can be extracted almost directly as poetry or short short fiction (also called “flash fiction”) an critiqued as such.