"Standard ML is a functional programming language, in the sense that the full power of mathematical functions is present." From a Pdf linked on the repo (I didn't know what Standard ML was, I was hoping for a mark up language)

StandardML is a rather nice modular high level functional programming language with algebraic datatypes, pattern matching, compile-time type checking and type inference etc. Poly/ML extends this with strong proven multi-core and cross platform support including Posix threads, parallel garbage collection, FFI etc. Poly/ML has been around a while, but it is still actively maintained by Dave Mathews et al (most recent release June 2026) has good windows and X11 support. Poly/ML is a great way to explore the world of StandardML and is used to build Isabelle and HOL theorem provers. Definitely worth a look!

See SGML for a markup language.