Not having subroutine signatures is plainly embarrassing.
Strangely enough, I've been programming in a variety of languages for over 30 years and this is the first time that I can remember coming across the term "subroutine signatures". But since moritz thinks they're crucially important it seemed only fair to find out what they are.
So, off I go to my default search engine and ask it about subroutine signatures. It turns out that they are just interfaces - essentially what would be described by a well-functioning prototype system. Presumably this precise term is used in some other branch of English which is why I haven't come across it before today.
However, the pertinent thing is that of the first 10 results (my arbitrary choice) returned by the search engine, fully 8 are specific to Perl (and one of the others is the wikipedia entry explaining the term). I was pleased to find that contrary to the doom and gloom in this thread and that perpetuated by the devotees of other languages more generally, Perl is actually at the forefront of discussions on some computational matters.
So let us not despair too much. For all those who would rally round and actively try to boost Perl's reputation, very good luck to you. The starting point is to my mind at least not so low as many might suggest.