By the way, is there difference between a homograph and polymorphism?

Several. For one thing, a homograph is not necessarily also a homophone (though it can be). Also, the different versions of a homograph may be different parts of speech in some cases; as far as I am aware, polymorphism keeps the polymorphic thing as the same part of speech. Furthermore, the idea behind polymorphism, if it's done correctly, is that there is supposed to be a logical connection or parallel between the different versions of it, a way in which, although slightly different, they are "the same"; this is sometimes botched, but it's *supposed* to be there; homographs have no such qualms.

Homographs like "wind" and "fly" and "record", wherein the meanings are related, are not the nasty ones, IMO. Situations like "that" (which is used as a relative pronoun, as a demonstrative pronoun or adjective, or as a subordinating adverb, and, worst of all, is frequently elided) are the rough ones. Perl as far as I am aware does not have any such pitfalls as that; even the weirdness surrounding pieces of punctuation (notably, commas and curly braces) has nothing on "that".