[autarchprinceps]

What would you use for a HPC application? You need a very fast language that doesn't get in your way in data management. Trust me even in the basic examples we did in our parallel algorithms course minor changes in data layout could save hours of computational time and that was in C, where no crappy garbage collection gets in your way. Not to even mention the masses of good low level performance analysation tools and parallel libraries made for Fortran and C/C++, but not other languages. Why would you use anything else? I think some people misunderstand what makes languages good. It is not generalisable, it depends on the case. Sure to write a script, e.g. to quickly automate a few things, shell or common scripting languages like ruby or python may make sense, because it is relatively easy to get going and write something in them. But that is not an important question for an HPC application. You need to write code that will definitively give the correct result and that will run extremely fast on the cluster of machines that make up the supercomputer. You need the language means to define very detailed how your memory is to be layed out, etc.. The very thing that makes a language annoying to use in a scripting context is a feature here. On the other hand you don't care about the ease of portability, in fact you will want to optimise it for one specific architecture as much as time allows. That the program will have to be recompiled is a minor issue in comparison to memory layout, threading schedules or network communication changes to the algorithm to optimise it for a new system.

No language is truely superior to all others, the question is always context and the conditions and constrictions it puts on the developer.

For physicists Fortran or C are the best choices. Even Go uses a garbage collector which brakes it for large HPC scenarios. VM based languages are completely useless. Their low speed is already a nuisance for simple common tasks, never mind problems that already take days or weeks to execute when they are properly optimised. If you think Java, Ruby or any such language could be used, look at benchmarks. You will find CPU time of 1.5-2.5x and memory at least 5-7x the amount needed by the same problem executed by a program written in C.