To be precise, a downward range is empty. For example,
print 0...1; print "\n";

[download]
produces the result
01

[download]
but inverting the 0 and 1 produces an empty line. z...a had no noticable effect -- still an empty line, but zzzzzzz...aaaaaaa did indeed cause perl to go into huddle while it was presumably calculating the combinations even though it should arguably know that it should promptly exit the range with an empty result when the second argument is lower than the first.

I consider this a missed optimisation opportunity in perl.

One world, one people

In reply to Re: Syntax error makes perl hang by anonymized user 468275
in thread Syntax error makes perl hang by VSarkiss

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