#inject and slowness
I've often heard Ruby's inject method criticized as being "slow." As I rather like the function, and see equivalents in other languages, I'm curious if it's merely Ruby's implementation of the method that's slow, or if it is inherently a slow way to do things (e.g. should be avoided for non-small collections)?
inject is like fold, and can be very efficient in other languages, fold_left specifically, since it's tail-recursive.