While I generally agree that the discretion must be observed when working on production code, I don't think the author is advocating these to be of wide use.
These are very useful when you play Perl Golf, and can be pretty powerful in the hands of an expert player (sadly, my dreams of becoming one has remained just that.)
The author of this document was a regular in Perl Golf tournaments and also in the Fun With Perl mailing list, which was a precursor and launchpad for several of these tournaments.
If I remember correctly, that would be "mtve" [1] (who sometimes went by a slightly longer "mtveurope"). If I had to pick the top three all-time Perl golfers, he would be one of them.
> From someone who loves Perl, please do not use it in production :)
From another someone who has written fair amount of perl, some of them are simple idioms suitable for production use; rest are just an exercise in curiosity.
The venus operator "0+ $input"(or `0 + $input` as I will write it) is an acceptable and recommended way to convert input to number(i.e if you know your your input is a valid number in string form). !! isn't unique to perl - I have used it in JS, C etc to convert a value to boolean. @{[ ]} is useful for logging, thought it does look difficult to grok in first look. Goatse is basically list assignment and then using it in scalar context; I won't do that but assigning to list is frequently done `my ($a, $b) = $input =~ /regex/`. =<>~ is just badly formatted `my ($a, $b) = <> =~ /regex/` will read fine to a perl programmer.
Very few of these are really unsuitable for production. High preference and conditional operation operators are probably the ones I would be most shocked to see.
The rest (especially goatse, venus and things like X-Wing) should be fairly intuitive from operator precedence.
Part of the problem, if you want to call it that, is probably that people like to put spaces in their code. This leads them to see magic, when in fact they're just insufficiently practiced at scanning the code as the computer sees it.
