In control engineering or instrumentation, I see Simulink or LabVIEW(G) is pretty popular. In ESL design, I see that Agilent SystemVue is gaining some popularity.

If you see the well established compiler theroy, almost 100% is about the textual language. But how about the graphical language?

Is there any noticable research or discussion about the graphical programming language? In terms of

• Theory about Graphical Language - syntactic/semantic analysis and whatever relevant
• expressiveness (Actually, I asked a question about it at SO - http://stackoverflow.com/questions/2427496/what-do-you-mean-by-the-expressiveness-in-programming-lanuguage)
• Possibility of the Graphical language
• ...

Or what do you think about the Graphical Programming Language?