[kazinator]

Leaving out rest args supports the syntactic sugar for currying, not currying itself. (Let's call that sugar OAIPA: omission of arguments is partial application.)

Even syntaxes which have OAIPA can (and do) still have optional parentheses to exactly delimit the arguments of a call, and that notation can clearly support variadic args.

Outside of explicit delimiting with parens, OAIPA can work on a variadic function up to its required arguments by considering it to be a function of exactly that number of arguments, and no more.