The underlying data is all binary, but LabVIEW has built-in diff tools that allow you to compare diagrams (the source code) between two vi's (LabVIEW files). As a result, you can use it with source control and coordinate multiple developers much like any other language. It isn't really necessary for the underlying data to be text. Search is also pretty decent.

The beauty of dataflow languages is that it frees the developer to think about what is really important while the runtime handles the nasty concurrency issues. Does this approach work for all problem domains? No, but it works fine for a lot of stuff. Nothing comes close to LabVIEW for making concurrency trivial.

Its a pity that LabVIEW and programming languages like it haven't seen much mainstream adoption. In the right hands and in the right problem domain, a good LabVIEW dev can do things that would make other programmers' jaws drop.

TL;DR:

Full Metal Jacket is a general purpose, pure dataflow language, supporting recursion, higher order functions, strong typing, type inference, and macros. It's entirely graphical, but it is possible to call Lisp.

It has a very simple, regular, syntax, with only vertices, edges, constants, and enclosures. No special syntax is required for conditions, iteration, or new type definitions. It is homoiconic, though I haven't yet made full use of that.

It is an alternative model of computation, potentially enabling different parts of an algorithm to run concurrently.

It is still under development.

It's implemented in Lisp, so the underlying data are Lisp data structures. Programs are stored as S-expressions, are not particularly easy to read or safe to modify.

I ended up doing roughly the same thing. The graph is based on text, stored in arrays in memory. I just convert to JSON to store on disk. You wouldn't want to mess with the JSON, but technically you could if you didn't make any mistakes.

You can't actually run the programs in parallel though, right? The structure is there but you'd need something on a chip to take advantage of it?

What you've built sounds very interesting, but this part is a problem you may need to solve before programmers will embrace it. If I can't use git with it, I can't develop any non-trivial software with it.

Technically, what git shows you is already a visual diff ;) and they like to draw the diff tree instead of describing it textually because it makes a lot more sense.

Transform:

    (a1 a2 (b1 b2))

    -------------
    parent  child
    -------------
    root    list1
    list1   a1
    list1   a2
    list1   list2
    list2   b1
    list2   b2