F

false:: n. the symbol nil, used to represent the failure of a predicate test.
fbound:: [ 'ef_'baünd ] adj. (of a function name) bound in the function namespace. (The names of macros and special operators are fbound, but the nature and type of the object which is their value is implementation-dependent. Further, defining a setf expander F does not cause the setf function (setf F) to become defined; as such, if there is a such a definition of a setf expander F, the function (setf F) can be fbound if and only if, by design or coincidence, a function binding for (setf F) has been independently established.) See the functions fboundp and symbol-function.
feature:: n. 1. an aspect or attribute of Common Lisp, of the implementation, or of the environment. 2. a symbol that names a feature₁. See Section 24.1.2 Features. The :ansi-cl feature is present in all conforming implementations.
feature expression:: n. A boolean combination of features used by the #+ and #- reader macros in order to direct conditional reading of expressions by the Lisp reader. See Section 24.1.2.1 Feature Expressions.
features list:: n. the list that is the value of *features*.
file:: n. a named entry in a file system, having an implementation-defined nature.
file compiler:: n. any compiler which compiles source code contained in a file, producing a compiled file as output. The compile-file function is the only interface to such a compiler provided by Common Lisp, but there might be other, implementation-defined mechanisms for invoking the file compiler.
file position:: n. (in a stream) a non-negative integer that represents a position in the stream. Not all streams are able to represent the notion of file position; in the description of any operator which manipulates file positions, the behavior for streams that don't have this notion must be explicitly stated. For binary streams, the file position represents the number of preceding bytes in the stream. For character streams, the constraint is more relaxed: file positions must increase monotonically, the amount of the increase between file positions corresponding to any two successive characters in the stream is implementation-dependent.
file position designator:: n. (in a stream) a designator for a file position in that stream; that is, the symbol :start (denoting 0, the first file position in that stream), the symbol :end (denoting the last file position in that stream; i.e., the position following the last element of the stream), or a file position (denoting itself).
file stream:: n. an object of type file-stream.
file system:: n. a facility which permits aggregations of data to be stored in named files on some medium that is external to the Lisp image and that therefore persists from session to session.
filename:: n. a handle, not necessarily ever directly represented as an object, that can be used to refer to a file in a file system. Pathnames and namestrings are two kinds of objects that substitute for filenames in Common Lisp.
fill pointer:: n. (of a vector) an integer associated with a vector that represents the index above which no elements are active. (A fill pointer is a non-negative integer no larger than the total number of elements in the vector. Not all vectors have fill pointers.)
finite:: adj. (of a type) having a finite number of elements. The type specifier (integer 0 5) denotes a finite type, but the type specifiers integer and (integer 0) do not.
fixnum:: n. an integer of type fixnum.
float:: n. an object of type float.
for-value:: adj. (of a reference to a binding) being a reference that reads₁ the value of the binding.
form:: n. 1. any object meant to be evaluated. 2. a symbol, a compound form, or a self-evaluating object. 3. (for an operator, as in "<<operator>> form") a compound form having that operator as its first element. A quote form is a constant form.
formal argument:: n. Trad. a parameter.
formal parameter:: n. Trad. a parameter.
format:: v.t. (a format control and format arguments) to perform output as if by format, using the format string and format arguments.
format argument:: n. an object which is used as data by functions such as format which interpret format controls.
format control:: n. a format string, or a function that obeys the argument conventions for a function returned by the formatter macro. See Section 22.2.1.3 Compiling Format Strings.
format directive:: n. 1. a sequence of characters in a format string which is introduced by a tilde, and which is specially interpreted by code which processes format strings to mean that some special operation should be performed, possibly involving data supplied by the format arguments that accompanied the format string. See the function format. In "~D base 10 = ~8R", the character sequences `~D' and `~8R' are format directives. 2. the conceptual category of all format directives₁ which use the same dispatch character. Both "~3d" and "~3,'0D" are valid uses of the `~D' format directive.
format string:: n. a string which can contain both ordinary text and format directives, and which is used in conjunction with format arguments to describe how text output should be formatted by certain functions, such as format.
free declaration:: n. a declaration that is not a bound declaration. See declare.
fresh:: adj. 1. (of an object yielded by a function) having been newly-allocated by that function. (The caller of a function that returns a fresh object may freely modify the object without fear that such modification will compromise the future correct behavior of that function.) 2. (of a binding for a name) newly-allocated; not shared with other bindings for that name.
freshline:: n. a conceptual operation on a stream, implemented by the function fresh-line and by the format directive ~&, which advances the display position to the beginning of the next line (as if a newline had been typed, or the function terpri had been called) unless the stream is already known to be positioned at the beginning of a line. Unlike newline, freshline is not a character.
funbound:: [ 'efunbaünd ] n. (of a function name) not fbound.
function:: n. 1. an object representing code, which can be called with zero or more arguments, and which produces zero or more values. 2. an object of type function.
function block name:: n. (of a function name) The symbol that would be used as the name of an implicit block which surrounds the body of a function having that function name. If the function name is a symbol, its function block name is the function name itself. If the function name is a list whose car is setf and whose cadr is a symbol, its function block name is the symbol that is the cadr of the function name. An implementation which supports additional kinds of function names must specify for each how the corresponding function block name is computed.
function cell:: n. Trad. (of a symbol) The place which holds the definition of the global function binding, if any, named by that symbol, and which is accessed by symbol-function. See cell.
function designator:: n. a designator for a function; that is, an object that denotes a function and that is one of: a symbol (denoting the function named by that symbol in the global environment), or a function (denoting itself). The consequences are undefined if a symbol is used as a function designator but it does not have a global definition as a function, or it has a global definition as a macro or a special form. See also extended function designator.
function form:: n. a form that is a list and that has a first element which is the name of a function to be called on arguments which are the result of evaluating subsequent elements of the function form.
function name:: n. 1. (in an environment) A symbol or a list (setf symbol) that is the name of a function in that environment. 2. A symbol or a list (setf symbol).
functional evaluation:: n. the process of extracting a functional value from a function name or a lambda expression. The evaluator performs functional evaluation implicitly when it encounters a function name or a lambda expression in the car of a compound form, or explicitly when it encounters a function special form. Neither a use of a symbol as a function designator nor a use of the function symbol-function to extract the functional value of a symbol is considered a functional evaluation.
functional value:: n. 1. (of a function name N in an environment E) The value of the binding named N in the function namespace for environment E; that is, the contents of the function cell named N in environment E. 2. (of an fbound symbol S) the contents of the symbol's function cell; that is, the value of the binding named S in the function namespace of the global environment. (A name that is a macro name in the global environment or is a special operator might or might not be fbound. But if S is such a name and is fbound, the specific nature of its functional value is implementation-dependent; in particular, it might or might not be a function.)
further compilation:: n. implementation-dependent compilation beyond minimal compilation. Further compilation is permitted to take place at run time. Block compilation and generation of machine-specific instructions are examples of further compilation.