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Hmm, I cannot say that I understand this. What does "evaluating an array" mean? Reversing the order of its elements? According to the manual cond is a ternary operator that returns one of its last two operands. The parentheses should only have an effect for the operand that it does not return, which is only relevant if it has a side effect. It says it always evaluates the operand that it does return, parentheses or not.

Is it that the parentheses in this context have special meaning, so that when you pass a bare array it strips the parentheses, and parses the operands differently? That still does not seem to explain how it could swap the order of the elements.

I was just wrestling with some other very mysterious behavior. I have an expression:

  set traded cond and match #victim #protected
                      match #mover #protected #mover 0;

This appears to make the variable traded (which was 0 before) disappear! A print #traded; directly behind it prints 'traded'. The problem is related to the fact that I tried to set protected to an empty array, though set protected ( ); . Apparently the parentheses are no good for this; when I replace it by set protected array; I really get an empty array, and the the problem disappears. When I print the individual sub-expressions match #victim #protected and match #mover #protected they both print as empty strings, in both cases, which seems to be the representation of false. So when those are the same no matter how I set protected, how can it still matter for the final result? How can a variable disappear because of an assignment anyway?