It's not hard to imagine an extension to ML-style types that could cover variadicity:
map : ('a... -> 'b) -> ('a list)... -> 'b list
Where <type>... denotes <type1> -> <type2> -> ... -> <typeN> spliced into the type signature, with each type variable 'a in <type> replaced with 'a1, 'a2, ... 'aN. You could cover tuples too:
zip : ('a list)... -> 'a,,, list
Bit ugly, and writing a type checker for it could be fun, but it seems workable.
Fully typing variadicity in Python is only possible with dependent typing, since Python allows you to build the argument list dynamically. Generally speaking you can't even determine the number of arguments statically:
args = []
while some_condition():
args.append('x')
f(*args)
Typed Racket allows you type some common cases, though.
