Some programming languages languish due to obscurity. They lack breathless blog posts exclaiming how much nicer they are to use. Other languages are too ambitious. They aspire to support so many features that the original implementers struggle to get a first version working. For example, the type system in Fortress required constraint solving which took exponential time. Sometimes a usable language struggles simply because it’s too much fun to write your own. Developers end up building their own...