Span in C#
C# was mostly irrelevant to me a long time when Microsoft's implementation was closed, but there are some neat things about it. They've done a lot of interesting stuff in the language since it first came out, including pragmatic sugar-y stuff like type inference (`var`), async/await, and recently some moves towards more functional-style pattern matching though they're not totally there yet (https://www.kenneth-truyers.net/2016/01/20/new-features-in-c... discusses proposals, some of which didn't make C# 7). Interfaces and value types also seemed like important things to have early, and there's some other handy looking stuff like the SustainedLowLatency GC mode (defer full-heap compactions as long as it can).Can be tempting to think of it as a Java clone because of its early history and the shared general category (OO-focused GC'd imperative statically typed language whose first major impl was bytecode/VM-based), but there's signs of more to it than that.