[tavert]

It's much easier and lower-overhead to call into C, Fortran, and soon even C++, from Julia than it is from Python. If there's a library in Python but not yet in Julia, it's really easy to call into Python from Julia.

What you can do in Julia that you can't do in Python is write high-performance library code in the high level language. If you need to write custom code that isn't just using stock numpy or scipy algorithms right out of the box, and needs to use custom data structures and user-defined types, Julia is a fantastic choice. You can try with Cython or Numba or PyPy, but you're either working with a limited subset of the language, or forgoing compatibility with most of the libraries that people use Python for.

Julia feels like writing Python but does not allow some of the semantically impossible-to-optimize behaviors that you can find in Python, and has a type system that you can use to your advantage in designing optimized data structures for the problem at hand.

[eva1984]

Thanks for explaining this.

As to my own experience dealing with data, the degree of freedom, as basically a programmer, is small. Specifically, I have to think and bear tools in my mind from the start. Which might not be ideal, but cant avoid anyway.