I always interpret "idiomatic" as "avoiding performance issues". In Python, for example, using the join method on strings is not only idiomatic, it's performant. Even if a particular idiom has no effect on performance, the worst that happens is I write idiomatic code. Not only that, but idiomatic coding allows me to write performant code without having to understand why it performs well. I don't know Ruby, so I can't comment on each vs for loops, but in general there's a practical, performance-based advantage to idiomatic coding.
> I always interpret "idiomatic" as "avoiding performance issues".
Huh? That is definitely not what it means. That may be a byproduct if the language implementers then make the social mores they admire the ones that perform the best, but otherwise that's not what makes something an idiom or a social more.
> That may be a byproduct if the language implementers then make the social mores they admire the ones that perform the best
I understand the definition of the word idiom. I'm saying that the quoted scenario is, in fact, not just hypothetical, but likely. Thus, following idiomatic style can help one avoid performance issues.
Not at all likely, and in fact if you believe this without first investigating its validity then you may be bit by bad performance. A very real scenario is that you use something blindly because everyone else does, thinking it performs well, and then you find out it actually doesn't.
Not always though. I don't know if this is still the case, but "while true" used to be more idiomatic in Python than "while 1" even though the latter had better performance due to the state of the cpython implementation at the time.
It may be the case that at any given point, the idiomatic way is not the fastest. However, if idioms are widely adopted, the language implementers have good reason to optimize them. I'm not saying that's what happened in this case, but I think it's reasonable claim to make in general.
