It's important to note that not every research area ends up being a surface-language, and oftentimes research projects remain in-progress for a long time. There does exist a freely available research implementation of a 1ML interpreter (though slightly behind the language's formalization) offered by the author:

https://people.mpi-sws.org/~rossberg/1ml/

The thing is that this is a research prototype, not a real compiler. It's not usable in the same degree as a language like SML or Haskell. There is a lot more work beyond a grammar that goes into creating a compiler for a high level language.