Your "supercompiler" phrase made me think about what happens if you start applying the partial evaluation over and over. Of course nothing happens... unless you

Your "supercompiler" phrase made me think about what happens if you start applying the partial evaluation over and over. Of course nothing happens... unless you know something more than what you knew before. Which you might! That in turn made me think of the Wolfram Language, which feels like this to me – you declare things, and as the set of declarations continues the language starts to "know" more things, and your statements become more concrete. This is interesting because it's all automated, you can undo things, change them, implicitly loop them by considering multiple possibilities. I'm not sure you could take Prepack and do this. But it sure seems interesting. A kind of partial evaluation coding notebook... not so unlike a symbolic spreadsheet I suppose.