[mwhite]

I meant that your code could parse the supposed lave code before running it to verify that it is limited to the known lave constructs (which does not include arbitrary code execution). It would quite slow but enough to make it somewhat safe against an attacker providing malicious lave code.

[mbrock]

If lave generates a well defined sublanguage, I don't think parsing would need to be much slower than parsing JSON. It would just be an extended JSON parser that happens to parse executable JavaScript.