NIL=() Considered Harmful

Consider function READ, which parses a list of elements or returns NIL on syntax error. Such READ function would provide no way to read an empty list, because return would be indiscernible from error. But Lisp indulges creation of such read functions, because checking for NIL is much easier than checking for exception.

Moreover, it breaks strong-typing, making harder to guess author's intention.


(a b c d)
(a . (b . (c . (d . T_PAAMAYIM_NEKUDOTAYIM))))
(b . (c . (d . T_PAAMAYIM_NEKUDOTAYIM)))
(c . (d . T_PAAMAYIM_NEKUDOTAYIM))
(d . T_PAAMAYIM_NEKUDOTAYIM)
T_PAAMAYIM_NEKUDOTAYIM