in reply to Perl is not Dynamically Parseable

Fallacious Conclusion: We can in general determine whether any Perl function has a nullary prototype or not.

It's not fallacious. There's no guarantee that the answer won't change later or that it'll be the same at the same point of execution in a different interpreter, but we can indeed determine whether any Perl function has a nullary prototype or not.

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Re^2: Perl is not Dynamically Parseable
by Jeffrey Kegler (Hermit) on Oct 12, 2009 at 06:01 UTC
    It's fallacious because you need to know you will reach the code which can make the determination. And to know, in general, that you will reach that nullarity-determining code you've got to know the answer to the Halting Problem in every form it can take. Being able to determine the nullarity of a Perl function, given arbitrary Perl code, amounts to being able to fully predict the operation of a Turing machine.
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      It's fallacious because you need to know you will reach the code which can make the determination

      That makes no sense. No matter what code is being compiled or executed, it can be determined whether any Perl function has a nullary prototype or not. No piece of Perl code needs to be reached.

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        Before returning to the subject of this thread, I'd like to point out that ikegami is one of the very best contributors to Perlmonks. The quality of his nodes is even higher than his experience ranking indicates. A monk once suggested that an efficient way to deepen your Perl knowledge is simply to go to the list of ikegami nodes, and read, read, read. I've done this several times, and I'm happy to pass the suggestion on.

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