It knows when to do escaping and how. It also can detect, though dynamically, when fragments have been combined into an illegal sequence which would be rejected by the full grammar. It can not however guarantee that the result will parse only that it can not detect that it would fail.
Was that a question? In that case, now I have :) The authors include both of the Eelcos I’ve ever heard of no less!
The ugly quasiquoting seems unfortunate (I’ve a half-serious suspicion the reason Template Haskell never got popular is that it looks so bad), and the GLR sledgehammer precludes ever having a lightweight implementation, but otherwise it seems like a interesting entry in the extensible languages story.
It knows when to do escaping and how. It also can detect, though dynamically, when fragments have been combined into an illegal sequence which would be rejected by the full grammar. It can not however guarantee that the result will parse only that it can not detect that it would fail.