in reply to Guess what it does ... and a challenge

I parsed that code correctly in my head, but didn't realize what the result would be.

Here is a program of the same length (as your second snippet) that does the same thing slowly:

blokhead

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Re^2: Guess what it does ... and a challenge
by locked_user mtve (Deacon) on May 31, 2008 at 19:35 UTC

      No, it won't. Now, if you do $_='a' first, then it will, and extremely slowly too.

      - tye        

        Damn, you're right, silly me. In golfy way:
        1while$~++
        Update: leaks here btw, 5.8.8 activestate