Those show that it's possible, not necessarily that it's a good interface to make those parts of programs. Houdini's shader language has had branching done in

Those show that it's possible, not necessarily that it's a good interface to make those parts of programs. Houdini's shader language has had branching done in a data flow graph for a long time. Touch designer has a kind of looping construct too. You might want to take a look at these domain specific interfaces if you are doing your own graph, they are well done. Fundamentally though, the density of text expressions exceeds a data flow graph by a huge margin. If what is being done isn't fundamentally a directed acyclic graph, visualizing it with a graph becomes more difficult to absorb than the expressions as text.