First of all I want to say that you are doing an excellent job. I program in Fortran and python but I'm keeping an eye on Julia, I haven't decided to switch yet. I'm not afraid to learn a new language, so I may do it in the future.
Python is slow, but most of the time I use vectorized instruction (with numpy), it is quite fast for what is needed (elaboration of experimental data). The python matplotlib graphics package is amazing. I know that it can be used from Julia, but when I tried it took some seconds to import it (not a big issue, but when you want to use it interactively it can). We have also lot of code already written in Python. That's not necessary a problem as once we already switched from Matlab to Python). If the speed is needed I can use Fortran, as it is quite easy to link a Fortran procedure to Python with f2py. The other pointed cited was true, when I tried to do something fast, I couldn't do it fast the first time (at the end I find a way to speed it up and was even faster than its Fortran equivalent). A lot of programs we have are mainly simulation program already written in Fortran so we may have to stick to it. There are also a couple of things, one is the use of the matlab points operator .*, ./, etc. Well I don't think it was really a good idea (at least for me). Most of the time all the operations I need are just point (how yo call them?) one and only few of them are really matrix operations. Of course it is not something that will keep me away from Julia but if there were ever be in future the possibility to change that behaviour.... (a daydream) I also liked a lot the possibility in numpy to add an axes to an array with the keyword numpy.newaxis. But I'm quite sure that wouldn't be a problem to add it to Julia (if it's not already possible of course, I'm waiting the final release of Julia 0.4 in order to have a new look at the new features). The other suggestion is to speed up vectorized instructions. The fact that in the manual is written to write explicit loops in places where even in Fortran one wouldn't have used loops anymore is a drawback. And last, it is psychological, but one is always waiting for the first stable release.... (when the 1.0...?) By the way I'm eager for the 0.4 release, I'll install it and I'l let you know my impressions.
