2.2 Classes of Primitive Data Types

The classes of primitive types are a notational convenience for describing the properties of functions.

boolean

The set of global variables {T,NIL}, or their respective values, {T, NIL}.

extra-boolean

Any value in the system. Anything that is not NIL has the boolean interpretation T.

ftype

The class of definable function types. The set of ids {EXPR, FEXPR, MACRO}.

number

The set of {integer, floating}.

constant

The set of {integer, floating, string, vector, function-pointer}. Constants evaluate to themselves (see the definition of EVAL in “The Interpreter”, section 3.14 on page 66).

any

The set of {integer, floating, string, id, dotted-pair, vector, function-pointer}. An S-expression is another term for any. All Standard LISP entities have some value unless an ERROR occurs during evaluation or the function causes transfer of control (such as GO and RETURN).

atom

The set {any}-{dotted-pair}.