[I tried to post this as a comment, but Zed decided to delete it :/] I think your comparison between for loops and .each is flawed - clearly you don't need to

[I tried to post this as a comment, but Zed decided to delete it :/] I think your comparison between for loops and .each is flawed - clearly you don't need to explain all those concepts in detail if at all. A for loop ultimately involves some level of polymorphism on the target collection, at least to the same level as required by the call to .each. I'd say that conceptually they are very similar, with both constructs having specific differentiating features. Also, .each doesn't eventually become a for-loop in C code. 1/ Neither Ruby nor Python are compiled to C code, and 2/ I wouldn't expect that the respective looping constructs become a typical C for loop, it is more likely they will be implemented in the native op-code (e.g. CPython, Ruby 1.9). With respect to why .each is fundamental to Ruby, we clearly see some key differences between Python and Ruby in this respect. I think the critical thing is that Ruby tends towards being a functional language while Python tends to be more imperative. We can see this clearly in the types of operations provided by Python, for example, list.reverse() in Ruby returns a copy of the list in reverse order, but in Python it reverses the list in place. Using .each in Ruby code leads to shorter more concise code in contrast to the corresponding Python code. Whether you feel that you are being judged or not (in a social sense) is probably a matter of who you choose to interact with on that level (e.g. a particular developer community). Have you ever had to use non-idomatic C code? How about non-idomatic Python code? Clearly, a big issue with source code is composition (on a project level) and non-idiomatic code causes many issues in this area. It is also interesting to note that non-idomatic behaviour plays a role in larger society. For example, choose the GPL and you might receive some complaints from communities that typically use MIT or BSD license. How about real life? If your friend buys you a drink and you don't play the social "ball game" (e.g. behave non-idomatically) you might have social problems in that area too. I think that ultimately you are confusing a social interaction with a programming language best practice. I don't think either of these things are bad - heck, look at all the company specific coding standards for C or C++ code - but ultimately whether you choose to indoctrinate your students into a particular social circle, or teach them the best practice for a given programming language is simply a matter of perspective; and empowering your students to understand why things are the way they are, rather than simply saying this is the way we've always done things, is ultimately something I think is very important.