I've just been reading about TextUML, which is a language and IDE for textually defining UML diagrams by a start-up company called abstratttechnologies.
This seems like both a stroke of brilliance and painfully obvious. It makes me wonder why UML isn't already defined in terms of a serializable language. The big advantage of this I think would be the ability to have a clearly defined semantics. In the past when reading about UML I've been quite frustrated by an apparent lack of rigour in the definition of the various UML concepts and diagrams. It's always seemed to me that a metalanguage like UML is more in need of fully-defined semantics than application languages. Most (all?) application languages after all are executable, which gives provides a final authority for the meaning of a program written in them - run it and see what happens. AFAIK UML isn't really (or not conveniently) executable in the same way.
Which brings me to the paradox promised in the title of this post. One of the claims for TextUML is that it is easier to write and express complex models in than a purely diagram-based UML tool. I can easily believe this - developing a complex model by diagrams seems cumbersome and limited compared to writing a textual description. And I think this generalizes to the concept of visual programming in general. We've had easy access to powerful graphics capabilities for over 20 years now, culminating in today's basically unlimited in graphical capabilities. In spite of this, text-base programming still rules the roost when it comes to expressiveness, flexibility and speed.
So the paradox is: why is a 1-dimensional representation more powerful than a 2-dimensional representation? To put this another way, why does a 1D representation seem less "flat" than a 2D representation?
For further study: would the same apply to a 3D representation? Or would a move to 3D jump out of some sort of planar well, and end up being more expressive than 1D?
By the way, abstratt is right here in l'il ol' Victoria, and the lead designer (and CEO) Rafael Chavez is giving a talk at VicJUG in March. I'm definitely going to attend - I suspect he may have an interesting take on this issue.