Re "Include.pi": It certainly is modular... but in the interest of readability (among other things), saving the keystrokes might be better done with a macro in your editor. Were I to read code such as you might write using this, I suspect I'd be expecting something on the order of 3.1416....

While C and perl have many relationships, perl does NOT always benefit from using C-style constructs: think for loops, for example.