I remember articles asking for this in the 80's. Shame no one listened. Guess we were all to busy programming to worry much about what the IDE (if there was one) could be doing. Here is an interesting example http://www.sorting-algorithms.com/ I've always resented as a code documentarian that I got no help from the one thing that knew what the hell was going on---the compiler! Sigh...
> If a programmer cannot see what a program is doing, she can't understand it.
I really agree with this. An aspect of any "new" programming language/environment should be continual and immediate feedback.