This code:

try {
    die "foobar\n";
    print "OK";
} catch {
    print "FAILED!\n";
};
[download]

Executes like this:

try( sub { die "Foobar"; print "OK"; },
     catch(sub { print "FAILED!\n"; })
   );
[download]

In other words, there are two arguments to try(): a coderef and whatever catch() returns (normally a coderef, its own first argument). So catch() has to be called before try() can be called.