I don't know how to make the code editor in Mathematica present the code in a real 'monospace' font, with a dark, customizable theme (syntax highlighting). This is something that keeps me away from working with Mathematica as my primary programming environment.

I mean, I like Mathematica, but I only use it as I used Derive in my old high-school days: as a powerful tool for symbolic mathematics, plus some nice 2D and 3D plots.

I would like to use Mathematica as my main framework for scientific programming, meaning:

• A customizable editor (in the terms I expressed at the beginning of this post).
• Separating code (files with functions and routines) from execution (console).
• A debugging environment.

Notebooks are OK, but can I have a classical programming environment?

Could you please help me with this basic question?