(work in progress! notes will be updated as generators are re-evaluated.)
Static site generators are far from a solved problem. It's a deceptively simple proposition: grab some data -- say, blog posts written in Markdown files -- stick them in templates, and spit out a set of HTML files, ready to be served as-is on something like GitHub Pages, no complex server code needed. And indeed, there have been hundreds of takes on the idea, running the gamut of pretty much every programming and templating language imaginable.