Explicit graphical flow-based systems have their own issues. If the logic is simple, the systems are manageable. However, complex logic very quickly leads to a

Explicit graphical flow-based systems have their own issues. If the logic is simple, the systems are manageable. However, complex logic very quickly leads to a very complex graph with huge number of lines criss-crossing each other, until they make no sense. Conal Elliot has done some interesting work in the area of "visual programming." The following is a good paper, but entirely academic: http://lambda-the-ultimate.org/node/2159 http://lambda-the-ultimate.org/node/2159.