That makes it possible, but far from easy/convenient enough to be worthwhile.

What I imagine is intended by this is a text editor tailor made for browsing and editing code on a touch screen with limited real estate. A non-trivial problem in my estimation.

iSSH+vim for iphone has a usable interface. I've actually done emergency work through it. But if you have a bluetooth keyboard it becomes even more usable. I figure it's about as usable as you'll get with the iphone's tiny screen and keyboard.

An iPad and a bluetooth keyboard is around as heavy or heavier than a 11" macbook air.

You can use an iphone and a roll up rubber keyboard, or a laser keyboard...