To sum up my part:
@giordano Here is a link to a little bit more info on this topic [Why Julia is very often related to a data science / economics language only? - #21 by j_u]. If you think that this might be to your interest just let me know.
@lmiq >But what other characteristics of the language are important in those very-high end supercomputers?
As is currently my general understanding on this subject, “those very-high end supercomputers”, are quite normal computers, and on most occasions, in reality, are pretty similar to the ones we use every day. As for Julia and its ecosystem, IMO, and not surprisingly, the most easy would be to use the ones build on x86 and Nvidia technologies. Also, there is currently a new clearly visible and worth mentioning trend related to high performance computations that are done in the cloud, the trend is called “democratization of HPC”, where some big cloud providers but also Julia Hub are prime examples. To try to answer you question more directly and with a smile, IMO, the main language characteristic would be that it just has to work there on “this very-high end supercomputer” and there has to be a team of people interested in a topic and willing to implement the solution.