Tony Finch's blog

Of course, if you're not committed to using the same main() for both versions of this, there's no reason the higher-order macro approach needs a table at all:

#define pred_justdoit(name, test) \
    if (test) { putsafe(#name); done = true; }

Then you can replace the for-loop that iterates over the predicate table with a simple predicates(pred_justdoit).