> dotted-list-p doesn't have anything to do with the "serialized form" (printed representation) of the list
It does: the details of the serialization are the reason that the concept of "dotted list" even exists. At the risk of belaboring the obvious, dotted lists are called "dotted lists" because there is a syntactically-significant dot in their serialization.
> There are many symbols in Common Lisp that you cannot DEFUN. See section 11.1.2.1.2 in the hyperspec.
It is not that you cannot defun them, it is that this is undefined behavior. At least one implementation (CCL) lets you defun just about everything except NIL:
? (defun &body () t)
&BODY
? (&body)
T
? (defun t () nil)
T
? (t)
NIL
But, as noted earlier...
? (defun nil () t)
> Error: Using NIL as a function name is silly.
> Since NIL names a constant variable but not a standardized function, macro, or special operator, you can bind it to a function lexically using FLET or LABELS.
NIL's lack of weirdness in this one regard actually seems pretty weird to me. IMHO it would actually makes sense to prohibit defining a function whose name is the same object that designates an empty list, just as it makes sense to prohibit defining functions whose names are (say) numbers.
> That operators treat a symbol specially does not make a symbol weird.
That all turns on how you define "weird". One dictionary definition of "weird" is "strikingly odd or unusual, especially in an unsettling way; strange". The fact that the CAR and CDR of NIL are both NIL seems weird to me. The fact that NIL is the canonical boolean false is NIL rather than F seems weird to me. (Actually, the canonical booleans, if they were going to be symbols at all, should have been :T and :F or :TRUE and :FALSE. But that's a different discussion.)
> Are you saying the symbol &BODY is not an ordinary symbol because it is a lambda list keyword?
Yes. Lambda-list keywords are weird. They behave differently from X and Y and Z and BAZ and BAR and BING and BIFF and BOFF and ORDINARY-SYMBOL and even WEIRD-SYMBOL. The same is true for symbols interned in the keyword package. All of these things are weird.
It does: the details of the serialization are the reason that the concept of "dotted list" even exists. At the risk of belaboring the obvious, dotted lists are called "dotted lists" because there is a syntactically-significant dot in their serialization.
> There are many symbols in Common Lisp that you cannot DEFUN. See section 11.1.2.1.2 in the hyperspec.
It is not that you cannot defun them, it is that this is undefined behavior. At least one implementation (CCL) lets you defun just about everything except NIL:
But, as noted earlier... > Since NIL names a constant variable but not a standardized function, macro, or special operator, you can bind it to a function lexically using FLET or LABELS.NIL's lack of weirdness in this one regard actually seems pretty weird to me. IMHO it would actually makes sense to prohibit defining a function whose name is the same object that designates an empty list, just as it makes sense to prohibit defining functions whose names are (say) numbers.
> That operators treat a symbol specially does not make a symbol weird.
That all turns on how you define "weird". One dictionary definition of "weird" is "strikingly odd or unusual, especially in an unsettling way; strange". The fact that the CAR and CDR of NIL are both NIL seems weird to me. The fact that NIL is the canonical boolean false is NIL rather than F seems weird to me. (Actually, the canonical booleans, if they were going to be symbols at all, should have been :T and :F or :TRUE and :FALSE. But that's a different discussion.)
> Are you saying the symbol &BODY is not an ordinary symbol because it is a lambda list keyword?
Yes. Lambda-list keywords are weird. They behave differently from X and Y and Z and BAZ and BAR and BING and BIFF and BOFF and ORDINARY-SYMBOL and even WEIRD-SYMBOL. The same is true for symbols interned in the keyword package. All of these things are weird.