Control flow in a dataflow language

A declarative visual language should describe operational algorithms easily if it is to be used for systems and application development: a causal transition model with temporal properties expressed as pre- and post-conditions must be a part of its semantics. The embedding of this `control flow´ within dataflow is analogous to the construction of `control flow´ CPUs using dataflow wires and registers, with hardware bits extended to software values drawn from the universal domain