T. Stephen Strickland Sam Tobin-Hochstadt Matthias Felleisen Practical Variable-Arity Polymorphism. 32-46 2009 ESOP http://dx.doi.org/10.1007/978-3-642-00590-9_3 conf/esop/2009 db/conf/esop/esop2009.html#StricklandTF09