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I had some didactic experience (programming basic courses for freashmen). First of all, I told the students that the choice of the programming language was an incidental fact. Not very important (we used Pascal).
Coding was only matter of translation from meta-language (used to develop a solution) to programming language.
It seems that using a natural language instead of another does not influence the way one thinks (I suggest reading Steven Pinker's The Language Instinct)
I'm not so sure of that for what concerns programming languages, in particular for Perl. In programming languages do exist different paradigms: it doesn't happen in natural languages. But this is another thread.
I was talking about my experience. My impression is that is not actually difficult to comprehend what a scalar or a vector is.
What seem really difficult to teach are structured programming principles and techniques. By-value- and by-reference calls, scope and so on. I don't mention recursion, that seems really hard (are you including it in your book?)
see you. larsen