Numba is trying to let you make a different choice for different sections of the same program so that you can do different styles of programming in code meant to be a library than you might do in other sections of code meant to be more "ocassional programmer" facing.
Some of you might find the roadmap particularly interesting. It's an open-source project eager for input from others...
choose two:
a. fast execution of the code on the machine
b. fast code generation by the programmer
c. fine-grained control over every aspect of the code
I know which two I'd rather have, esp in the long run.