Hotwire: a combined terminal/GUI for GNU/Linux (Free Software Magazine)

It depends on how you look at it.

With python you avoid the source --> compile --> linker cycle. You just edit the source code,
add your functions to a library or to a directory, and the compiling and that sort of thing is
done on the fly. 

With bash you'd have to get the source code and edit it to extend it, unless you use a plugin
or extension feature like you mentioned just now.

That being said, I like the idea of a script-based shell. It's very similar to Emacs.. the
major difference here is that hotwire isn't going to pretend its a editor to trick programmers
into trying it out. :)

After playing around with hotwire I've decided that I like the concept very much. If the
keybindings can be made to be theme-able then it should be simple to make my own screen-like,
vi-like bindings.

Any thoughts on a mode-based shell? :)