variablein

Variablein is a term used in programming and data modeling to denote an input variable within a computation or dataflow. It is not an official keyword in mainstream languages, but appears in discussions, tutorials, and some domain-specific languages as a way to distinguish input variables from internal state or outputs.

Origin and use: The construction blends "variable" with the preposition "in," echoing how some languages designate inputs with keywords such as in, from, or input ports. In practice, variablein is often used as a label or annotation rather than a runtime keyword. In dataflow and component-based design, ports labeled variablein mark external data sources feeding a node or function.

Examples: In a hypothetical DSL, a function might declare its inputs as "variablein a" and "variablein b," with internal computations producing "variableout c." In a strongly typed language example: process(variablein x: Int, variablein y: Int) -> Int. This clarifies intent and can help tooling separate inputs from outputs.

Alternatives: Operators and conventions such as parameters, arguments, input ports, and in/out annotations serve similar roles. The concept of a variablein emphasizes the direction of data flow and external provenance rather than the role of the value inside the function.

See also: parameter, argument, input port, in/out, dataflow, DSL.