Discovered an interesting failure mode of my evaluation model: ->> is undefinable because macro-symbols are unable to delay the evaluation of sublists. Normally this is not a problem, but function expansion is value-preserving only for argument lists of equal length. (e.g. (->> [1 2] (map1 inc)) fails). Not sure how much I need to fix here, but this seems like a good opportunity to formalize levels of quotation.