#Variadic Generics
Status: language specification draft.
hd has no variadic generics: no type packs, no value packs, and no pack expansion. This chapter keeps its number so that links to it survive, and it states no rules.
Code that works over every arity uses ordinary tuples instead:
| Need | Mechanism |
|---|---|
| a parameter that collects any number of arguments of any types | a vararg whose type is a type parameter bounded by Tuple, as in args...: Args (Varargs) |
| a function of any arity | Fn[Args, O, $ R] or SuspendFn[Args, O, $ R] with Args < Tuple (Function Type Constructors) |
| a call with a tuple of arguments | a tuple spread, f(args...) (Positional Spreads) |
| awaiting children of different result types | the intrinsic all!, whose result is a tuple (Standard Combinators) |
| equality, ordering, and hashing of tuples | derived by the compiler for every arity (Implementation Targets) |
use std.function.{Fn, Tuple}
fn call[Args < Tuple, O, $R](f: Fn[Args, O, $ R], args...: Args) -> O $ R:
f(args...)
fn add(a: i32, b: i32) -> i32: a + b
fn three() -> i32: call(add, 1, 2)Note. Packs were removed by owner decision Q9 of batch 31, on 2026-09-30.