> The goal of a compiler author is that their language live.
No it isn't. The goal is that the language is useful over time while discounting the future. Languages should die eventually when the circumstances thamade them useful change.
We shouldn't prevent language from dying, but they shouldn't either due to lack of maintenance.
Also, thanks for the feedback!
Languages in the first class should die quickly. They're intended to be for research. They tend to have a longer lifetime than they should when people use these languages for commercial use. Languages in the second class should be long-lived as the systems depending on them may be long lived. Some of the useful language features from the research languages may be introduced into the software engineering languages. C++ is a great example of this as it has been borrowing concepts from research languages for some time now.