Vital visual notations?

Martin Ewig wrote (snipped)

I think that some visual notations are more readable than text (but not all). In particular, if you try to teach lambda calculus or type inference to beginners, visual notations can be extremely helpful.

For some people, perhaps. I don't have a very good mind for visual things and I much prefer symbolic versions of lambda calculus. Perhaps beginners need to be shown it both ways.