Rust

Rust aims to be a language empowering everyone to build reliable and efficient software. It features performance on part with C++, combined with high level features (such as algebraic data types) inspired by OCaml. Rust's tooling and ecosystem offer a first class developer experience: standard package management, friendly error messages, and a large, inclusive community. Rustaceans often cite the language as proof that systems programmers can have nice things.

The one truly esoteric feature of Rust is borrow checking, aka Rust's "secret sauce." The borrow checker supports automatically managed, deterministic object lifetimes: the performance of manual memory management, with the safety of (or really, better than) a garbage collector. The borrow checker allows at most one mutable reference to any object at any time, preventing data races.

Chief criticisms of Rust are its steep learning curve and slow, disk-hungry builds. Rust is arguably the poster child for esoteric language features, as the language went from a single developer's project at Mozilla to one of the best known commercially successful languages in the world in only about a decade. On the back of this popularity, other languages (both esoteric and mainstream) have also begun sprouting borrow checkers. Regardless of Rust's popularity or decline going forward, its influence has been undeniable.