Any serious programming language has a variety of collections in its library. Most reduce the resulting complexity by overloading the common operations for multiple types. But few include
cons among the generic operations. This is partly because it's unnatural for many types - only the functional collections like lists and trees support it efficiently. But it may also be a problem that the operation has no obvious name.
Dylan calls it
add, which sounds like arithmetic. Clojure calls it
conjoin, which is unfortunately confusable with the complex conjugate function. C++ has
push, but that's implicitly imperative. Other possibilities:
with, or maybe a more abstract symbol like
&. Does anyone have a better idea?