jsgrep looks very neat as well. I like the patch syntax. However, I don't think this example is quite equivalent. In the grasp example, it replaces every binary operator, not just that specific call. Could you show how to represent the same thing in jsgrep?
Not possible in jsgrep without enumerating all of the binary options (I can't think of a good reason for needing to do that though). It's more suited for doing API changes:
