variadically

Variadic describes a function, operation, or construct that accepts a variable number of arguments. The adverb variadically denotes performing such an action. The term is used in mathematics, statistics, and computer science and stems from Latin varius, meaning "varied," combined with the -adic suffix. Variadic behavior contrasts with fixed-arity functions, which require a predetermined number of inputs.

In mathematics, variadic notation is used for sequences like sum(a1, a2, ..., an) or product(a1, a2, ..., an), where the number of operands is not fixed. In computer science, variadic functions allow callers to pass an arbitrary number of arguments. Many languages provide mechanisms to handle variadic inputs. In C, a function declared with ... is variadic and access to arguments is via va_list and va_arg. In Python, the *args parameter collects extra positional arguments, and **kwargs collects extra keyword arguments. In JavaScript, rest parameters ...args gather additional arguments. In Java, varargs use the syntax ..., and in Kotlin, varargs function similarly. In C++, variadic templates enable compile-time handling of arbitrary argument lists. Not all languages support variadic functions for both positional and keyword arguments, and some impose limits on the number of arguments or require explicit packing into a collection.

Considerations for variadic constructs include type checking, argument processing, and performance. Some languages wrap variadic inputs into a container type (such as a list or array) for uniform processing, while others rely on stack-based retrieval. Variadic design also interacts with function overloading, default arguments, and calling conventions. The notion extends beyond functions to operators and macros in some languages, where operators may accept a variable number of operands.