Talk:First-class citizen/to do


 * The article does not properly reflect that the concept of "first-classness" is vague, fluid and sometimes arbitrary in practice. There is no fixed set of criteria that is necessary or sufficient to for something to be called a "first-class x". This is highly dependent on both the value of x and person first coining the term "first-class x" for some x.
 * Cleaveland, An Introduction to Data Types: orthogonality in ALGOL 68
 * First-class modules (ML), First-class phantom types (Cheney & Hinze), first-class data types/levitation (McBride)