skynight is correct that Perl 5 contains some fundamental semantic traps.

It does, but only when you're used to different semantics. Perl was my second programming language, but different enough from BASIC to assume no rule would be the same. I never fell into any of its well known traps. (I tend to get bitten by the more obscure semantics.)

In the same way, HOP says it changes the way you code Perl because it assumes you learned Perl after learning C, or you learned Perl from someone who was familiar with C. For me, this was never true. I'm trained by the logic provided in perldocs, which means that I don't code like a C coder. In fact, I'm almost halway through HOP and although it's a terrific book that I am glad I bought, I still hope to find new ways of coding, because to me, the Perlish way of things feels most natural already.

length(@foo) returning 2 for a 13 element @foo has never surprised me. It was through contact with many beginners (here and in EFnet #perlhelp) that I discovered that this really is a trap for many.

skynight is correct that Perl 5 contains some fundamental semantic traps.

It does, but only when you're used to different semantics. Perl was my second programming language, but different enough from BASIC to assume no rule would be the same. I never fell into any of its well known traps. (I tend to get bitten by the more obscure semantics.)

Well, that's certainly an interesting point -- sometimes it's better for different things to look different so you won't get them confused -- but it's actually fundamentally different from the way perl was originally conceived. It was supposed to look a lot like things that programmers were already familiar with, so it would make them feel like they knew what was going on.

And I think the larger point here is that it's really okay to criticize the way something was done in perl. You can be totally committed to perl culture and still think that type globs were a mess.

(Or course, these days it's a little late to bother criticizing perl 5, since the design of perl 6 is pretty well fixed.)

My experience is similar. There are some things I have misunderstood in Perl and confused myself, but they are not the typical things, because my language background is atypical. I too started in BASIC, then later Inform (hence most of my ideas about OO) and subsequently elisp. (Ironically, I did not get my ideas about FP from elisp; I never understood FP in elisp but have picked it up (err, some of it) since I learned Perl.)

This is an important point in this thread, because it illustrates that what constitutes a "trap" utterly depends on what language you think in, what semantics you are used to. The first time I saw someone posting on here about the print($a+$b)*$c; trap, I thought he was out of his mind. I had no idea why he was multiplying the result of the print by a scalar in void context, or what it was he intended to accomplish by doing so, because I don't think in C. (I figured it out eventually, partly by looking at some of the answers to his question, but it was quite a surreal moment when I first looked at his code.) Is that a trap? It sure as death and taxes wasn't a trap for me. It's only a trap if you are accustomed to thinking in a certain fashion, which is not universal and happens not to be the least bit Perlish. It's a common trap *mostly* because so many people come to Perl from a C or C-like language background; otherwise, it would not be a trap at all.

I don't think it's possible to eliminate all the traps for people coming from other languages, because each other language will have its own set of traps. When you move from one language to another, you should expect to get caught by a few of these misunderstandings until you learn to think in the new language. As long as you're still thinking in another language and translating, you're going to get confused sometimes. That's unavoidable.

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"In adjectives, with the addition of inflectional endings, a changeable long vowel (Qamets or Tsere) in an open, propretonic syllable will reduce to Vocal Shewa. This type of change occurs when the open, pretonic syllable of the masculine singular adjective becomes propretonic with the addition of inflectional endings."  — Pratico & Van Pelt, BBHG, p68

I don't quite agree with that sentiment. That "trappiness" of any given language feature is indeed a function of your linguistic background, but that's not the only thing at play. You can also have pitfalls that are entirely internal to a language simply because two syntactically similar operations have subtle but important semantic differences. I think the whole () / [] distinction serves as a decent example of this. In Python, such a flub is not possible, whereas in Perl it most certainly is.