> But why can't we just have a vector type that tolerates that and does something well-defined? What if we actually want to modify the list while iterating, because we are filtering the list for example?
This adds overhead that’s not always desired. And sometimes, this ends up being a logic bug. There are languages where this produces a result instead of being UB, but it’s almost always shown off as a “can you believe this wacky behavior” because it’s not intuitive. From a random search I just did: https://stackoverflow.com/questions/12232788/adding-to-an-ar...
This adds overhead that’s not always desired. And sometimes, this ends up being a logic bug. There are languages where this produces a result instead of being UB, but it’s almost always shown off as a “can you believe this wacky behavior” because it’s not intuitive. From a random search I just did: https://stackoverflow.com/questions/12232788/adding-to-an-ar...