D. It's not based on an ML-ish type system, but the amazing metaprogramming capabilities allowed std.variant.visit (sum type matching) to be implemented in nor

D. It's not based on an ML-ish type system, but the amazing metaprogramming capabilities allowed std.variant.visit (sum type matching) to be implemented in normal library code: https://dlang.org/blog/2018/03/29/std-variant-is-everything-cool-about-d/ https://dlang.org/blog/2018/03/29/std-variant-is-everything-... immutability is not default too… but on the other hand, there's @nogc and betterC mode, purity annotations, contract programming, C++ (!) interop, an option to use the "C-ish" linking model (to build with e.g. Meson instead of Dub, install dynamic libs system-wide, and so one), and again, just next level metaprogramming. You can do anything with Rust procedural macros, but they give you a token stream and you drag in the rust parser as a dependency and operate on the raw AST. That's hard and "special". With D metaprogramming you can, for example, just `static foreach` over the list of the current class's members directly inline where you want it.