The Odin programming language very recently merged in support for Haiku:
On the project’s website, Odin is described as “The Data-Oriented Language for Sane Software Development” having distinct typing made with high performance, modern systems, and data-oriented programming in mind. One of the most notable software written with Odin is EmberGen by VFX software development studio JangaFX, a real-time volumetric fluid simulator often used in big-budget productions.
From the Odin perspective Haiku is considered to be technically a Unix-like OS, despite the pull request’s creator saying that it isn’t. The PR author also notes that futex (fast userspace mutex) is simulated through the libc, taking inspiration from this article on creating a futex implementation. The PR author hopes to get in touch with the Haiku developers in improving the reliability of said futex implementation.