Editing Dataflow programming (section)

===Representation===
Dataflow programs are represented in different ways. A traditional program is usually represented as a series of text instructions, which is reasonable for describing a serial system which pipes data between small, single-purpose tools that receive, process, and return. Dataflow programs start with an input, perhaps the [[command line]] parameters, and illustrate how that data is used and modified. The flow of data is explicit, often visually illustrated as a line or pipe.

In terms of encoding, a dataflow program might be implemented as a [[hash table]], with uniquely identified inputs as the keys, used to look up pointers to the instructions. When any operation completes, the program scans down the list of operations until it finds the first operation where all inputs are currently valid, and runs it. When that operation finishes, it will typically output data, thereby making another operation become valid.

For parallel operation, only the list needs to be shared; it is the state of the entire program. Thus the task of maintaining state is removed from the programmer and given to the language's [[Run-time system|runtime]]. On machines with a single processor core where an implementation designed for parallel operation would simply introduce overhead, this overhead can be removed completely by using a different runtime.