Pharo can already communicate natively with objective C and all its libraries via Nativeboost. An example is Mars on Pharo.
Nativeboost of course can communicate with C and it even offers an inline Assembler so you can go down to bare metal having all the speed and performance you want.
Nativeboost cannot communicate with C++ currently , so it cant use C++ libraries like VTK , however there is a workaround.
Overall when dealing with C/C++ you have to deal with all sort of technically issues that you don't have in pharo. The problem also becomes even worse because C/C++ libraries usually are not made with simplicity in mind. In the case for example of CAD software with pharo this is of course doable but you will need to have a very deep understanding how 3d graphics works which is a highly technically area by itself. So as you can see there are loads of technically problems to overcome even before worrying about Pharo.
But none the less its doable. ��