> If the same program is behaving differently between two systems - it can -only- be the environment that’s different. Yes, but the entire problem is that "the

> If the same program is behaving differently between two systems - it can -only- be the environment that’s different. Yes, but the entire problem is that "the environment" is massive as it includes all hardware and software running on the device in question (and quite possible other devices as the network can easily be considered part of "the environment") which makes it difficult to track down differing behaviour. "The environment" is not just environment variables. I've run into a spreadsheet bug where I got wrong results because of a CPU bug. Just because some global mutable state exists, that doesn't mean it's a good software design to have program behaviour depend on it.