[analog31]

I don't think I'm gonna be able to "reword" this for people here so it suddenly clicks, you're probably just going to need to see it in action to understand it.

So called "visual" programming languages like LabVIEW and Visual Basic seem to come very close. There's a supervisory program that manages and parses inputs, and schedules the invocation of functions when those inputs change. I'm not sure what those programs do with the outputs of functions is exactly what the author proposes, but you could let the supervisory program route the outputs of functions to their desired effects.

Definition of the expected input format and its interpretation, and likewise for the output format, would presumably be done in some meta-programming language.

My Visual Basic programs contained little or no input/output code, until I started using VB to control industrial machines.