This may sound arrogant, but - to what level of programmers? I can count on the fingers of one hand (with several to spare) the number of times I got myself in a bind with closures. As the old adage goes, real programmers can write FORTRAN in every language - I doubt anyone who makes a mess with Perl would write clean and sophisticated code if just given another language.

I don't want to close the post on that note; I understand your concern and know just taking the indoctrinated stance on this doesn't make the problems in practice go away. But in my experience trading expressiveness for simplicity does not pay off in the long run. ("Simplicity" is not quite the right word either.)

People often don't realize that this is a closure:

my $q = CGI->new()

sub foo {
    my $thing = $q->param('thing');
}
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Then they try to use it in a persistent environment like mod_perl or FastCGI and they get screwed. I see this happen all the time.

For at least my own education, if no one elses, how exactly is that a closure and why are people getting screwed doing it? It seems fairly simple to me..