What puzzles me about Jolla and it's Sailfish OS is the constant emphasis on being "truly open" when in fact the sources of the OS are nowhere to be found. They point you to projects such as Mer and say Sailfish OS is based on it but by the same logic Apple is "truly open" because OS X is based on Darwin.
Mono OTOH might be okayish for C#, but for instance F# so far has no open source implementation. Also Mono is lacking w.r.t. TCO and GC, so its not even close to a decent VM for functional languages.
This VM is based on LLVM and in particular aimed at parallel programming. As its author said: "HLVM is an experiment to see what a next-generation implementation of a language like OCaml might look like, addressing all of OCaml's major shortcomings (interoperability, parallelism and some performance issues)." [http://caml.inria.fr/pub/ml-archives/caml-list/2009/09/a94db...]
Not quite true. Looking at the type signature of e.g. RWArc::write I see this:
which means I could probably do: