% -*- Mode: TeX -*-		   

%%% ========== NIL
\begincom{nil}\ftype{Type}

\label Supertypes::
all \term{types}

\label Description::

\Thetype{nil} contains no \term{objects} and so is also
called the \term{empty type}.
%% 2.15.0 5
\Thetype{nil} is a \term{subtype} of every \term{type}.
No \term{object} is \oftype{nil}.

\label Notes::

The \term{type} containing the \term{object} \nil\ is \thetype{null},
not \thetype{nil}.

\endcom%{nil}\ftype{Type}

%%% ========== BOOLEAN
\begincom{boolean}\ftype{Type}

\label Supertypes::

\typeref{boolean},
\typeref{symbol},
\typeref{t}

\label Description::

\Thetype{boolean} contains the \term{symbols} \misc{t} and \misc{nil},
which represent true and false, respectively.

\label See Also::

\misc{t} (\term{constant variable}),
\misc{nil} (\term{constant variable}),
\specref{if},
\funref{not},
\funref{complement}

\label Notes::

Conditional operations, such as \specref{if},
permit the use of \term{generalized booleans},
not just \term{booleans};
any \term{non-nil} value,
not just \misc{t},
counts as true for a \term{generalized boolean}.
However, as a matter of convention, 
the \term{symbol} \misc{t} is considered the canonical value to use
even for a \term{generalized boolean} when no better choice presents itself.

\endcom%{boolean}\ftype{Type}

%Number and its subtypes moved to dict-numbers.
%Character and its subtypes moved to dict-characters.
%System Class SYMBOL moved to dict-symbols.
%Type KEYWORD moved to dict-symbols.
%Type SEQUENCE moved to dict-sequence.
%Type LIST, NULL, CONS, ATOM, ... moved to dict-conses.
%Types ARRAY, STRING, etc. to dict-strings.

%% new definition here?
%%% ========== FUNCTION
\begincom{function}\ftype{System Class}

\issue{FUNCTION-TYPE:X3J13-MARCH-88}

\label Class Precedence List::
\typeref{function},
\typeref{t}

\label Description::

A \term{function} is an \term{object} that represents code 
to be executed when an appropriate number of arguments is supplied.
%Removed per symbolics comments:
% A \term{function} can be supplied as an
%argument without error to \funref{funcall} or \funref{apply}.
A \term{function} is produced by 
 \thespecform{function},
 \thefunction{coerce},
\issue{SYNTACTIC-ENVIRONMENT-ACCESS:RETRACTED-MAR91}
%the \thefunction{enclose},
\endissue{SYNTACTIC-ENVIRONMENT-ACCESS:RETRACTED-MAR91}
or
 \thefunction{compile}.
A \term{function} can be directly invoked by using it as the first argument to
\funref{funcall}, \funref{apply}, or \specref{multiple-value-call}.

%!!! Barrett says this syntax is confused.
% Issues: &allow-other-keys, &key in value-typespec, &key mis-formatted where it already is.
\label Compound Type Specifier Kind::

Specializing.

\label Compound Type Specifier Syntax::

%% 4.5.0 12
\Deftype{function}{\ttbrac{arg-typespec \brac{value-typespec}}}

\auxbnf{arg-typespec}{\lparen\starparam{typespec}            \CR
		      \ \ttbrac{{\opt} \starparam{typespec}} \CR
                      \ \ttbrac{{\rest} \param{typespec}}    \CR
                      \ \ttbrac{{\key} \starparen{keyword typespec}}\rparen}

\label Compound Type Specifier Arguments::

\param{typespec}---a \term{type specifier}.

\param{value-typespec}---a \term{type specifier}.

\label Compound Type Specifier Description::

\editornote{KMP: Isn't there some context info about ftype declarations to be merged here?}

\editornote{KMP: This could still use some cleaning up.}%!!!

\editornote{Sandra: Still need clarification about what happens if the
number of arguments doesn't match the FUNCTION type declaration.}

The list form of the \typeref{function} \term{type-specifier}
can be used only for declaration and not for discrimination.
Every element of this \term{type} is
% I think the ``at least'' is confusing.  --sjl 7 Mar 92
% a \term{function} that accepts arguments at least of the
a \term{function} that accepts arguments of the
types   
specified by the  \param{argj-types} and returns values that are
members of the \term{types} specified by \param{value-type}. The
\keyref{optional}, \keyref{rest}, \keyref{key}, 
\issue{FUNCTION-TYPE-KEY-NAME:SPECIFY-KEYWORD}
and \keyref{allow-other-keys} 
\endissue{FUNCTION-TYPE-KEY-NAME:SPECIFY-KEYWORD}
markers can appear in the list of argument types. 
\issue{FUNCTION-TYPE-REST-LIST-ELEMENT:USE-ACTUAL-ARGUMENT-TYPE}
The \term{type specifier} provided
with \keyref{rest} is the \term{type} 
of each actual argument, not the \term{type} of the
corresponding variable.
\endissue{FUNCTION-TYPE-REST-LIST-ELEMENT:USE-ACTUAL-ARGUMENT-TYPE}
 
\issue{FUNCTION-TYPE-KEY-NAME:SPECIFY-KEYWORD}
The \keyref{key} parameters 
should be supplied as lists of the form {\tt (\param{keyword} \param{type})}.  
The \param{keyword} must be a valid keyword-name symbol
as must be supplied in the actual arguments of a
call.
\issue{KEYWORD-ARGUMENT-NAME-PACKAGE:ANY}
This is usually a \term{symbol} in \thepackage{keyword} but can be any \term{symbol}.
\endissue{KEYWORD-ARGUMENT-NAME-PACKAGE:ANY}
% tweaked to be less wordy  --sjl 7 Mar 92
%The \keyref{allow-other-keys} declarations are interpreted as follows:
%when \keyref{key} is given in a
%\declref{function} \term{type specifier} \term{lambda list}, 
%it is safe to assume that the \term{keyword parameters} given
When \keyref{key} is given in a
\declref{function} \term{type specifier} \term{lambda list},
the \term{keyword parameters} given
are exhaustive unless \keyref{allow-other-keys} is also present. 
\keyref{allow-other-keys} is an indication 
that other keyword arguments might actually be
supplied and, if supplied, can be used. 
For example,
the \term{type} of \thefunction{make-list} could be declared as follows:

\code
 (function ((integer 0) &key (:initial-element t)) list)
\endcode
\endissue{FUNCTION-TYPE-KEY-NAME:SPECIFY-KEYWORD}

The \param{value-type} can be a \declref{values} 
\term{type specifier} in order to indicate the
\term{types} of \term{multiple values}.


\issue{FUNCTION-TYPE-ARGUMENT-TYPE-SEMANTICS:RESTRICTIVE}
%{The following will be deleted:}
%
%
%%% 4.5.0 13
%For example, \thefunction{cons} is of type \f{(function (t t) cons)},
%because it can accept any two arguments and always returns a \term{cons}.
%%%see FUNCTION-TYPE-ARGUMENT-TYPE-SEMANTICS; cons isn't of the following type.
%\funref{cons} is also of type {\tt (function (float string) list)}, 
%because it can
%accept a \term{float}
%and a \term{string} (among other things), and its
%result is always \oftype{list}            
%(in fact a \term{cons} is never \term{null},
%but that does not matter for this type declaration).
%\funref{truncate} is of type 
%{\tt (function (number number) (values number number))}, 
%as well as of type
%{\tt (function (integer (mod 8)) integer)}.
%
%{End of deletion.}

Consider a declaration of the following form:
                                   
\code
 (ftype (function (arg0-type arg1-type ...) val-type) f))
\endcode
 
Any \term{form}
{\tt (f arg0 arg1 ...)}
within the scope of
that declaration is equivalent to the following:
 
\code
 (the val-type (f (the arg0-type arg0) (the arg1-type arg1) ...))
\endcode
 
That is, the consequences are undefined if any of the arguments are
not of the specified \term{types} or the result is not of the
specified \term{type}. In particular, if any argument is not of the
correct \term{type}, the result is not guaranteed to be of the
specified \term{type}.
 
Thus, an \declref{ftype} declaration for a \term{function}
describes \term{calls} to the \term{function}, not the actual definition
of the \term{function}.

Consider a declaration of the following form:

\code
 (type (function (arg0-type arg1-type ...) val-type) fn-valued-variable)
\endcode
 
This declaration has the interpretation that, within the scope of the
declaration, the consequences are unspecified if the value of {\tt
fn-valued-variable} is called with arguments not of the specified
\term{types}; the value resulting from a valid call will be of type
{\tt val-type}.

As with variable type declarations, nested declarations
imply intersections of \term{types}, as follows:
\beginlist
\itemitem{\bull} 
Consider the following two
declarations of \declref{ftype}:

\code
 (ftype (function (arg0-type1 arg1-type1 ...) val-type1) f))
\endcode
and

\code
 (ftype (function (arg0-type2 arg1-type2 ...) val-type2) f))
\endcode
 
If both these declarations are in effect,
then within the shared scope of the declarations, calls to {\tt f} can be
treated as if {\tt f} were declared as follows:

\code
 (ftype (function ((and arg0-type1 arg0-type2) (and arg1-type1 arg1-type2 ...) ...)
                  (and val-type1 val-type2)) 
        f))
\endcode
 
%!!! Barmar: what does this mean?
%    KMP: This is ill-worded and out of place. 
It is permitted to ignore one or all of the \declref{ftype} declarations in force.
 
\itemitem{\bull} 
If two (or more) type declarations are in effect for a variable, and
they are both {\tt function} declarations, the declarations combine similarly.
\endlist
 
\endissue{FUNCTION-TYPE-ARGUMENT-TYPE-SEMANTICS:RESTRICTIVE}

\endissue{FUNCTION-TYPE:X3J13-MARCH-88}

\endcom%{function}\ftype{System Class}

%%% ========== COMPILED-FUNCTION
\begincom{compiled-function}\ftype{Type}

\issue{FUNCTION-TYPE:X3J13-MARCH-88}


\label Supertypes::

\typeref{compiled-function},
\typeref{function},
\typeref{t}

\label Description::

\issue{COMPILED-FUNCTION-REQUIREMENTS:TIGHTEN}
Any \term{function} may be considered by an \term{implementation} to be a 
a \term{compiled function} if it contains no references to \term{macros} that
must be expanded at run time, and it contains no unresolved references 
to \term{load time values}.  \Seesection\CompilationSemantics.
\endissue{COMPILED-FUNCTION-REQUIREMENTS:TIGHTEN}

%% 2.13.0 2
\term{Functions} whose definitions appear lexically within a
\term{file} that has been \term{compiled} with \funref{compile-file} and then
\term{loaded} with \funref{load} are \oftype{compiled-function}.
\issue{COMPILED-FUNCTION-REQUIREMENTS:TIGHTEN}
\term{Functions} produced by the \funref{compile} function
are \oftype{compiled-function}.
\endissue{COMPILED-FUNCTION-REQUIREMENTS:TIGHTEN}
Other \term{functions} might also be \oftype{compiled-function}.
%but \funref{compile} does not necessarily produce a \term{compiled function}.

\endissue{FUNCTION-TYPE:X3J13-MARCH-88}

\endcom%{compiled-function}\ftype{Type}

%%% ========== GENERIC-FUNCTION
\begincom{generic-function}\ftype{System Class}

\issue{JUN90-TRIVIAL-ISSUES:9}
\label Class Precedence List::

\typeref{generic-function},
\typeref{function},
\typeref{t}
\endissue{JUN90-TRIVIAL-ISSUES:9}

\label Description::

A \newterm{generic function} is a \term{function} whose behavior
depends on the \term{classes} or identities of the \term{arguments}
supplied to it.  A generic function object contains a set of
\term{methods}, a \term{lambda list}, a \term{method combination} \term{type}, 
and other information.  The \term{methods}
define the class-specific behavior and operations of the \term{generic function};
a \term{method} is said to \term{specialize} a \term{generic function}.
When invoked, a \term{generic function} executes a subset of its
\term{methods} based on the \term{classes} or identities of its \term{arguments}.

A \term{generic function} can be used in the same ways that an
ordinary \term{function} can be used; specifically, a \term{generic function} can
be used as an argument to \funref{funcall} and \funref{apply},
and can be given a global or a local name.

\endcom%{generic-function}\ftype{System Class}

%%% ========== STANDARD-GENERIC-FUNCTION
\begincom{standard-generic-function}\ftype{System Class}

\label Class Precedence List::
\typeref{standard-generic-function},
\typeref{generic-function},
\typeref{function},
\typeref{t}

\label Description::

\Theclass{standard-generic-function} is the default \term{class} of
\term{generic functions} \term{established} by
\macref{defmethod},
\funref{ensure-generic-function},
\macref{defgeneric},
\issue{GENERIC-FLET-POORLY-DESIGNED:DELETE}
% \macref{generic-function},
% \specref{generic-flet},
% \specref{generic-labels},
\endissue{GENERIC-FLET-POORLY-DESIGNED:DELETE}
\issue{WITH-ADDED-METHODS:DELETE}
%\specref{with-added-methods},
\endissue{WITH-ADDED-METHODS:DELETE}%
and
\macref{defclass} \term{forms}.

\endcom%{standard-generic-function}\ftype{System Class}

%random-state moved to dict-numbers 

%conditions moved to dict-conditions, some perhaps to move again

%%% ========== CLASS
\begincom{class}\ftype{System Class}

\issue{JUN90-TRIVIAL-ISSUES:9}
\label Class Precedence List::
\typeref{class},
\issue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{standard-object},
\endissue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{t}
\endissue{JUN90-TRIVIAL-ISSUES:9}

\label Description::

%!!! Barrett: Since none of this can be accessed portably,
%    why specifically mention any of it?
\Thetype{class} represents \term{objects} that determine the structure 
and behavior of their \term{instances}. Associated with an \term{object}
\oftype{class} is information describing its place in the 
directed acyclic graph of \term{classes}, its \term{slots}, and its options.
%% Barrett: No! This is a gross AMOPism.
%and information about the \term{methods} that mention this \term{class} as a specializer.

% I had a terrible time figuring out what these paragraphs were trying
% to say until I realized what cleanup issue they were from.  I've moved
% this text to the discussion of built-in types in the classes concepts
% section, where there is more context for it.  --sjl 7 Mar 92
%\issue{CONDITION-SLOTS:HIDDEN}
%It is \term{implementation-dependent} whether \term{slots} are involved in the
%operation of \term{functions} defined in this specification
%on \term{instances} of \term{classes} defined in this specification,
%except when \term{slots} are explicitly defined by this specification.
%
%If in a particular \term{implementation} a \term{class} defined in this specification
%has \term{slots} that are not defined by this specfication, the names of these \term{slots}
%must not be \term{external symbols} of \term{packages} defined in this specification nor
%otherwise \term{accessible} in \thepackage{cl-user}.
%\endissue{CONDITION-SLOTS:HIDDEN}

\endcom%{class}\ftype{System Class}

%%% ========== BUILT-IN-CLASS
\begincom{built-in-class}\ftype{System Class}

\label Class Precedence List::
\typeref{built-in-class},
\typeref{class},
\issue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{standard-object},
\endissue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{t}

\label Description::

A \term{built-in class} is a \term{class} whose \term{instances} have 
restricted capabilities or special representations.
%!!! Barrett: The rest of this looks like a duplication of text a few pages back.
Attempting to use
\macref{defclass} to define \term{subclasses} of a \term{built-in class}
signals an error \oftype{error}.
Calling \funref{make-instance} to create an \term{instance} 
of a \term{built-in class} signals an error \oftype{error}.
Calling \funref{slot-value} on an \term{instance} of a \term{built-in class}
signals an error \oftype{error}.  Redefining a \term{built-in class}
or using \funref{change-class} to change the \term{class} of an \term{instance}
to or from a \term{built-in class} signals an error \oftype{error}.
However, \term{built-in classes} can be used as \term{parameter specializers}
in \term{methods}.
%!!! Barrett: Other ops also signal errors.
%    See SLOT-VALUE-METACLASSES
%Any \term{class} that corresponds to a standard
%\clisp\ type specified in \CLtL\ 
%might be an instance of \typeref{built-in-class}.
%The predefined Common Lisp \term{type specifiers} that are required to have
%corresponding classes are listed in \figref\ClassTypeCorrespondence.  It is implementation
%dependent whether each of these classes is implemented as a built-in class.

\endcom%{built-in-class}\ftype{System Class}

%%% ========== STRUCTURE-CLASS
\begincom{structure-class}\ftype{System Class}

\label Class Precedence List::

\typeref{structure-class},
\typeref{class},
\issue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{standard-object},
\endissue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{t}

\label Description::

All \term{classes} defined by means of \macref{defstruct} 
are \instsofclass{structure-class}.

\endcom%{structure-class}\ftype{System Class}

%%% ========== STANDARD-CLASS
\begincom{standard-class}\ftype{System Class}

\label Class Precedence List::
\typeref{standard-class},
\typeref{class},
\issue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{standard-object},
\endissue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{t}

\label Description::

\Theclass{standard-class} is the default \term{class} of \term{classes}
defined by \macref{defclass}.

\endcom%{standard-class}\ftype{System Class}

%%% ========== METHOD
\begincom{method}\ftype{System Class}

\issue{JUN90-TRIVIAL-ISSUES:9}
\label Class Precedence List::
\typeref{method},
\typeref{t}
\endissue{JUN90-TRIVIAL-ISSUES:9}

\label Description::

A \term{method} is an \term{object} that represents a modular part of the behavior
of a \term{generic function}.

A \term{method} contains \term{code} to implement the \term{method}'s
behavior, a sequence of \term{parameter specializers} that specify when the
given \term{method} is applicable, and a sequence of \term{qualifiers}
that is used by the method combination facility to distinguish among
\term{methods}.  Each required parameter of each 
\term{method} has an associated \term{parameter specializer}, and the 
\term{method} will be invoked only on arguments that satisfy its 
\term{parameter specializers}.

The method combination facility controls the selection of 
\term{methods}, the order in which they are run, and the values that are
returned by the generic function.  The \CLOS\ offers a default method
combination type and provides a facility for declaring new types of
method combination.

\label See Also::

{\secref\GFsAndMethods}

\endcom%{method}\ftype{System Class}

%%% ========== STANDARD-METHOD
\begincom{standard-method}\ftype{System Class}

\label Class Precedence List::
\typeref{standard-method},
\typeref{method},
\issue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{standard-object},
\endissue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{t}

\label Description::

\Theclass{standard-method} is the default \term{class} of 
\term{methods} defined by the 
 \macref{defmethod} and
 \macref{defgeneric} \term{forms}.
\issue{GENERIC-FLET-POORLY-DESIGNED:DELETE}
% \macref{generic-function},
\endissue{GENERIC-FLET-POORLY-DESIGNED:DELETE}
\issue{WITH-ADDED-METHODS:DELETE}
%\specref{with-added-methods},
\endissue{WITH-ADDED-METHODS:DELETE}%
%  \specref{generic-flet},
% and
%  \specref{generic-labels} \term{forms}.

\endcom%{standard-method}\ftype{System Class}

%%% ========== STRUCTURE-OBJECT
\begincom{structure-object}\ftype{Class}

\issue{JUN90-TRIVIAL-ISSUES:9}
\label Class Precedence List::

\typeref{structure-object},
\typeref{t}
\endissue{JUN90-TRIVIAL-ISSUES:9}

\label Description::

% \Theclass{structure-object} is a \term{superclass} of
% every \term{class} that is defined by \macref{defstruct}.
\Theclass{structure-object} is an \term{instance} of \typeref{structure-class}
and is a \term{superclass} of every \term{class} 
that is an \term{instance} of \typeref{structure-class}
except itself, and is a \term{superclass} of every \term{class} 
that is defined by \macref{defstruct}.

\issue{DATA-TYPES-HIERARCHY-UNDERSPECIFIED}%
%% Barrett: This is bogus.  I think there is enough other text in the draft
%%    (the first bullet in ``Type Relationships'' plus the definition of
%%    \term{system class}) to cover the requirements specified by 
%%    DATA-TYPES-HIERARCHY-UNDERSPECIFIED that this could simply be removed.
% The following \term{type specifier} \term{symbols} do not name
% \term{structure} \term{types} in any \term{implementation}:
% \typeref{cons}, \typeref{symbol}, \typeref{array}, 
% \typeref{number},
% \typeref{character}, \typeref{hash-table}, 
% \typeref{readtable}, \typeref{package}, \typeref{pathname}, 
% \typeref{stream}, or
% \typeref{random-state}.
% It is \term{implementation-dependent}
% whether other \term{standardized} \term{type specifiers} name structure types. 
\endissue{DATA-TYPES-HIERARCHY-UNDERSPECIFIED}

\label See Also::

\macref{defstruct},
{\secref\SharpsignS},
{\secref\PrintingStructures}

\endcom%{structure-object}\ftype{Class}

%%% ========== STANDARD-OBJECT
\begincom{standard-object}\ftype{Class}

\label Class Precedence List::
\typeref{standard-object},
\typeref{t}

\label Description::

\Theclass{standard-object} is an \term{instance} of \typeref{standard-class}
and is a \term{superclass} of every \term{class} that is an \term{instance} of
\typeref{standard-class} except itself.
% and
%\typeref{structure-class}.

\endcom%{standard-object}\ftype{Class}

%%% ========== METHOD-COMBINATION
\begincom{method-combination}\ftype{System Class}

\label Class Precedence List::
\typeref{method-combination},
\typeref{t}

\label Description::

Every \term{method combination} \term{object} is an 
\term{indirect instance} of the \term{class} \typeref{method-combination}.
A \term{method combination} \term{object} represents the information about
the \term{method combination} being used by a \term{generic function}.
A \term{method combination} \term{object} contains information about
both the type of \term{method combination} and the arguments being used
with that \term{type}.

\endcom%{method-combination}\ftype{System Class}

%%% ========== T
%% 2.0.0 6
\begincom{t}\ftype{System Class}

\label Class Precedence List::
\typeref{t}

\label Description::
The set of all \term{objects}.  
%% 2.15.0 4
\Thetype{t} is a \term{supertype} of every \term{type}, 
including itself. Every \term{object} is \oftype{t}.

\issue{COMMON-TYPE:REMOVE}
% Reference to type COMMON removed, and moved to Appendix A.
\endissue{COMMON-TYPE:REMOVE}

\endcom%{t}\ftype{System Class}

%%% ========== SATISFIES
\begincom{satisfies}\ftype{Type Specifier}

\label Compound Type Specifier Kind::

Predicating.

\label Compound Type Specifier Syntax::

\Deftype{satisfies}{predicate-name}

\label Compound Type Specifier Arguments::

\param{predicate-name}---a \term{symbol}.

\label Compound Type Specifier Description::
%% 4.3.0 1
%\itemitem
%{\tt (satisfies \param{predicate-name})} 
                                             
This denotes the set of all \term{objects} that satisfy the
\term{predicate} \param{predicate-name}, which must be a \term{symbol}
whose global \term{function} definition is a one-argument
predicate.  A name is required for \param{predicate-name}; 
\term{lambda expressions} are not allowed.
For example, the \term{type specifier} {\tt (and integer (satisfies evenp))}
denotes the set of all even integers.
The form {\tt (typep \param{x} '(satisfies \param{p}))} is equivalent to
{\tt (if (\param{p} \param{x}) t nil)}.
% The call {\tt (typep x '(satisfies p))} results in applying
% \f{p} to \f{x} and returning \f{t} if the result is \term{true} and \nil\ if the
% result is \term{false}.
%% 4.3.0 2                                   
%% I don't like the following example because it presupposes that standard-char-p is not
%  defined in terms of typep. -kmp 24-Oct-90
% For example, \thetype{standard-char} could be defined as follows:
% 
% \code
%  (deftype standard-char () '(and character (satisfies standard-char-p)))
% \endcode

\issue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}
The argument is required.
The \term{symbol} \misc{*} can be the argument, but it
denotes itself (the \term{symbol} \misc{*}),
and does not represent an unspecified value.

The symbol \typeref{satisfies} is not valid as a \term{type specifier}.
\endissue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}


\endcom%{satisfies}\ftype{Type Specifier}

%%% ========== MEMBER
\begincom{member}\ftype{Type Specifier}

\label Compound Type Specifier Kind::

Combining.

\label Compound Type Specifier Syntax::

\Deftype{member}{\starparam{object}}

\label Compound Type Specifier Arguments::

\param{object}---an \term{object}.

\label Compound Type Specifier Description::
%% 4.4.0 3
%\itemitem
%{\tt (member \starparam{object})}
%{\tt (member \param{object1} \param{object2} ...)}

This denotes the set containing the named \param{objects}. An
\term{object} is of this \term{type} if and only if it is \funref{eql}
to one of the specified \param{objects}.

\issue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}
The \term{type specifiers} \f{(member)} and \nil\ are equivalent.
\misc{*} can be among the \param{objects},
but if so it denotes itself (the symbol \misc{*}) 
and does not represent an unspecified value.
The symbol \misc{member} is not valid as a \term{type specifier};
and, specifically, it is not an abbreviation for either \f{(member)} or \f{(member *)}.
\endissue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}

\label See Also::

\thetype{eql}

\endcom%{member}\ftype{Type Specifier}

%%% ========== NOT
\begincom{not}\ftype{Type Specifier}

\label Compound Type Specifier Kind::

Combining.

\label Compound Type Specifier Syntax::

%% 4.4.0 4
\Deftype{not}{typespec}

\label Compound Type Specifier Arguments::

\param{typespec}---a \term{type specifier}.

\label Compound Type Specifier Description::

This denotes the set of all \term{objects} that are not of the \term{type} \param{typespec}.

\issue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}
The argument is required, and cannot be \misc{*}.

The symbol \typeref{not} is not valid as a \term{type specifier}.
\endissue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}

\endcom%{not}\ftype{Type Specifier}

%%% ========== AND
\begincom{and}\ftype{Type Specifier}

\label Compound Type Specifier Kind::

Combining.

\label Compound Type Specifier Syntax::

%% 4.4.0 5
\Deftype{and}{\starparam{typespec}}

\label Compound Type Specifier Arguments::

\param{typespec}---a \term{type specifier}.

\label Compound Type Specifier Description::
  
This denotes the set of all \term{objects} of the \term{type} 
determined by the intersection of the \param{typespecs}.

\issue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}
\misc{*} is not permitted as an argument.

The \term{type specifiers} \f{(and)} and \t\ are equivalent.
The symbol \misc{and} is not valid as a \term{type specifier},
and, specifically, it is not an abbreviation for \f{(and)}.
\endissue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}

\endcom%{and}\ftype{Type Specifier}

%%% ========== OR
\begincom{or}\ftype{Type Specifier}

\label Compound Type Specifier Kind::

Combining.

\label Compound Type Specifier Syntax::

%% 4.4.0 7 
\Deftype{or}{\starparam{typespec}}

\label Compound Type Specifier Arguments::

\param{typespec}---a \term{type specifier}.

\label Compound Type Specifier Description::
                               
This denotes the set of all \term{objects} of the
\term{type} determined by the union of the \param{typespecs}.
For example, \thetype{list} by definition is the same as \f{(or null cons)}.
Also, the value returned by \funref{position} is an \objectoftype{(or null (integer 0 *))};
\ie either \nil\ or a non-negative \term{integer}.

\issue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}
\misc{*} is not permitted as an argument.

The \term{type specifiers} \f{(or)} and \nil\ are equivalent.
The symbol \typeref{or} is not valid as a \term{type specifier};
and, specifically, it is not an abbreviation for \f{(or)}.
\endissue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}

\endcom%{or}\ftype{Type Specifier}

%%% ========== VALUES
\begincom{values}\ftype{Type Specifier}

\label Compound Type Specifier Kind::

Specializing.

\label Compound Type Specifier Syntax::

\Deftype{values}{\down{value-typespec}}

\reviewer{Barmar: Missing \keyref{key}}%!!!

\auxbnf{value-typespec}{\starparam{typespec}
			\ttbrac{{\opt} {\starparam{typespec}}}
			\ttbrac{{\rest} typespec}
			\ttbrac{\keyref{allow-other-keys}}}

\label Compound Type Specifier Arguments::

\param{typespec}---a \term{type specifier}.

\label Compound Type Specifier Description::

%% 4.5.0 14                                                    
%\itemitem{\tt (values \starparam{value-type})}
%\itemitem{\tt (values \param{value1-type} \param{value2-type} ...)}

This \term{type specifier} can be used only as the \param{value-type} in a
\typeref{function} \term{type specifier} or a \specref{the}
\term{special form}.  It is used to specify individual \term{types} 
when \term{multiple values} are involved.
The \keyref{optional} and \keyref{rest} markers can appear in the \param{value-type} list;
they indicate the parameter list of a \term{function} that, 
when given to \specref{multiple-value-call} along with the values,
%would be suitable for receiving those values.
would correctly receive those values.

\issue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}
The symbol \misc{*} may not be among the \param{value-types}.

The symbol \misc{values} is not valid as a \term{type specifier};
and, specifically, it is not an abbreviation for \f{(values)}.
\endissue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}

\endcom%{values}\ftype{Type Specifier}

%%% ========== EQL
\begincom{eql}\ftype{Type Specifier}

\label Compound Type Specifier Kind::

Combining.

\label Compound Type Specifier Syntax::

\Deftype{eql}{object}

\label Compound Type Specifier Arguments::

\param{object}---an \term{object}.

\label Compound Type Specifier Description::

Represents the \term{type} whose only \term{element} is \param{object}.

\issue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}
The argument \param{object} is required.  The \param{object} can be \misc{*},
but if so it denotes itself (the symbol \misc{*}) 
and does not represent an unspecified value.
The \term{symbol} \misc{eql} is not valid as an \term{atomic type specifier}.
%% Laubsch thinks this second part is gratuitous (and I agree). -kmp 20-Jan-92
%and, specifically, it is not an abbreviation for \f{(eql *)}.
\endissue{TYPE-SPECIFIER-ABBREVIATION:X3J13-JUN90-GUESS}

\endcom%{eql}\ftype{Type Specifier}

%%% ========== COERCE
\begincom{coerce}\ftype{Function}

\label Syntax::

\DefunWithValues coerce {object result-type} {result}

\label Arguments and Values::

\param{object}---an \term{object}.

\param{result-type}---a \term{type specifier}.

\param{result}---an \term{object}, of \term{type} \param{result-type}
  except in situations described in \secref\RuleOfCanonRepForComplexRationals.
    
\label Description::

%% 4.8.0 3
\term{Coerces} the \param{object} to \term{type} \param{result-type}.

If \param{object} is already of \term{type} \param{result-type},
the \param{object} itself is returned, regardless of whether it
would have been possible in general to coerce an \term{object} of 
some other \term{type} to \param{result-type}.

%% 4.8.0 4
Otherwise, the \param{object} is \term{coerced} to \term{type} \param{result-type}
according to the following rules:

\beginlist

\itemitem{\typeref{sequence}}

\issue{CONCATENATE-SEQUENCE:SIGNAL-ERROR}
% If the \param{result-type} is a \term{subtype} of \typeref{list},
% the result will be a \term{list}.
% 
% If the \param{result-type} is a \term{subtype} of \typeref{vector},
% then if the implementation can determine the element type specified
% for the \param{result-type}, the element type of the resulting array 
% is the result of \term{upgrading} that element type; or, if the
% implementation can determine that the element type is unspecified (or \f{*}),
% the element type of the resulting array is \typeref{t};
% otherwise, an error is signaled.

If the \param{result-type} is a \term{recognizable subtype} of \typeref{list},
and the \term{object} is a \term{sequence},
then the \param{result} is a \term{list} 
that has the \term{same} \term{elements} as \param{object}.

If the \param{result-type} is a \term{recognizable subtype} of \typeref{vector},
and the \term{object} is a \term{sequence},
then the \param{result} is a \term{vector} 
that has the \term{same} \term{elements} as \param{object}.
If \param{result-type} is a specialized \term{type}, 
the \param{result} has an \term{actual array element type} that is the result of
\term{upgrading} the element type part of that \term{specialized} \term{type}.
If no element type is specified, the element type defaults to \typeref{t}.
If the \term{implementation} cannot determine the element type, an error is signaled.

% I don't understand this and I can't figure out where it came from.
% It's stated below that an error is signaled if the appropriate result
% cannot be constructed.  --sjl 7 Mar 92
%The consequences are undefined if the \param{result} is not of \term{type} 
%\param{result-type}.
\endissue{CONCATENATE-SEQUENCE:SIGNAL-ERROR}

\itemitem{\typeref{character}}

If the \param{result-type} is \typeref{character}
and the \term{object} is a \term{character designator},
the \param{result} is the \term{character} it denotes.

\issue{CHARACTER-LOOSE-ENDS:FIX}
%Reference to INT-CHAR removed.
\endissue{CHARACTER-LOOSE-ENDS:FIX}

\itemitem{\typeref{complex}}

%% 4.8.0 7
If the \param{result-type} is \typeref{complex} 
and the \term{object} is a \term{number},
then the \param{result} is obtained by constructing a \term{complex}
whose real part is the \term{object} and
whose imaginary part is the result of \term{coercing} an \term{integer} zero
to the \term{type} of the \term{object} (using \funref{coerce}).
(If the real part is a \term{rational}, however, 
then the result must be represented as a \term{rational} rather
than a \term{complex}; \seesection\RuleOfCanonRepForComplexRationals.
So, for example, \f{(coerce 3 'complex)} is permissible,
but will return \f{3}, which is not a \term{complex}.)

\itemitem{\typeref{float}}

%% 4.8.0 6
If the \param{result-type} is any of \typeref{float},
 \typeref{short-float}, 
 \typeref{single-float}, 
 \typeref{double-float}, 
 \typeref{long-float},
and the \term{object} is a 
\issue{REAL-NUMBER-TYPE:X3J13-MAR-89}
\term{real},
\endissue{REAL-NUMBER-TYPE:X3J13-MAR-89}
then the \param{result} is a \term{float} of \term{type} \param{result-type}
which is equal in sign and magnitude to the \term{object} to whatever degree of
representational precision is permitted by that \term{float} representation.
(If the \param{result-type} is \typeref{float}
and \param{object} is not already a \term{float}, 
then the \param{result} is a \term{single float}.)

\issue{FUNCTION-TYPE:X3J13-MARCH-88}
\itemitem{\typeref{function}}

If the \param{result-type} is \typeref{function},
and \param{object} is any 
\issue{COERCING-SETF-NAME-TO-FUNCTION:ALL-FUNCTION-NAMES}
%% Barmar asked what about (COERCE '(SETF symbol) 'FUNCTION)
%% Mail sent to Quinquevirate. -kmp 3-Jun-91
%% This change was the result of that discussion. kmp 14-May-93
%\term{symbol}
\term{function name}
\endissue{COERCING-SETF-NAME-TO-FUNCTION:ALL-FUNCTION-NAMES}
that is \term{fbound} 
but that is globally defined neither as a \term{macro name} nor as a \term{special operator},
then the \param{result} is the \term{functional value} of \param{object}.

If the \param{result-type} is \typeref{function},
and \param{object} is a \term{lambda expression},
then the \param{result} is a \term{closure} of \param{object}
in the \term{null lexical environment}.
\endissue{FUNCTION-TYPE:X3J13-MARCH-88}

\itemitem{\typeref{t}}

%% 4.8.0 8
Any \param{object} can be \term{coerced} to an \term{object} \oftype{t}.
In this case, the \param{object} is simply returned.

\endlist

\label Examples::

\code
 (coerce '(a b c) 'vector) \EV #(A B C)
 (coerce 'a 'character) \EV #\\A
 (coerce 4.56 'complex) \EV #C(4.56 0.0)
 (coerce 4.5s0 'complex) \EV #C(4.5s0 0.0s0)
 (coerce 7/2 'complex) \EV 7/2
 (coerce 0 'short-float) \EV 0.0s0
 (coerce 3.5L0 'float) \EV 3.5L0
 (coerce 7/2 'float) \EV 3.5
 (coerce (cons 1 2) t) \EV (1 . 2)
\endcode

\issue{SEQUENCE-TYPE-LENGTH:MUST-MATCH}
All the following \term{forms} should signal an error:

\code
 (coerce '(a b c) '(vector * 4))
 (coerce #(a b c) '(vector * 4))
 (coerce '(a b c) '(vector * 2))
 (coerce #(a b c) '(vector * 2))
 (coerce "foo" '(string 2))
 (coerce #(#\\a #\\b #\\c) '(string 2))
 (coerce '(0 1) '(simple-bit-vector 3))
\endcode
\endissue{SEQUENCE-TYPE-LENGTH:MUST-MATCH}

\label Affected By:\None.

\label Exceptional Situations::

If a coercion is not possible, an error \oftype{type-error} is signaled.

\f{(coerce x 'nil)} always signals an error \oftype{type-error}.

An error
%KMP: I'm not sure UNDEFINED-FUNCTION is the right error type to signal here.
%Barrett: Yeah. This isn't really right for `fbound but not function'. Make it ERROR.
%KMP: Done
\oftype{error} is signaled
if the \param{result-type} is \typeref{function} but
\param{object} is a \term{symbol} that is not \term{fbound} or
if the \term{symbol} names a \term{macro} or a \term{special operator}.

\issue{SEQUENCE-TYPE-LENGTH:MUST-MATCH}
An error \oftype{type-error} should be signaled if \param{result-type}
specifies the number of elements and \param{object} is of a different length.
\endissue{SEQUENCE-TYPE-LENGTH:MUST-MATCH}

\label See Also::

\funref{rational}, \funref{floor}, \funref{char-code}, \funref{char-int}

\label Notes::

%% 4.8.0 9
Coercions from \term{floats} to \term{rationals} 
and from \term{ratios} to \term{integers} 
are not provided because of rounding problems.  

\code
 (coerce x 't) \EQ (identity x) \EQ x
\endcode

\endcom

%%% ========== DEFTYPE
\begincom{deftype}\ftype{Macro}

\issue{DECLS-AND-DOC}

\label Syntax::

\DefmacWithValues deftype {name lambda-list {\DeclsAndDoc} \starparam{form}} {name}

\label Arguments and Values::

\param{name}---a \term{symbol}.

\param{lambda-list}---a \term{deftype lambda list}.

\param{declaration}---a \misc{declare} \term{expression}; \noeval.

%% 4.7.0 4
\param{documentation}---a \term{string}; \noeval.

\param{form}---a \term{form}.

\label Description::

%% 4.7.0 2
\funref{deftype} defines a \term{derived type specifier} named \param{name}.

The meaning of the new \term{type specifier} is given in terms of
%tweaked  --sjl 7 Mar 92
%a body of code which expands the \term{type specifier} into another
a function which expands the \term{type specifier} into another
\term{type specifier}, which itself will be expanded if it contains
references to another \term{derived type specifier}.

The newly defined \term{type specifier} may be referenced as a list of
the form {\tt (\param{name} \param{arg$\sub{1}$} \param{arg$\sub{2}$} ...)\/}.
The number of arguments must be appropriate to the \param{lambda-list}.
If the new \term{type specifier} takes no arguments, 
or if all of its arguments are optional, 
the \term{type specifier} may be used as an \term{atomic type specifier}.

The \term{argument} \term{expressions} to the \term{type specifier},
\param{arg$\sub{1}$} $\ldots$ \param{arg$\sub{n}$}, are not \term{evaluated}.
Instead, these \term{literal objects} become the \term{objects} to which
corresponding \term{parameters} become \term{bound}.

The body of the \funref{deftype} \term{form} 
\issue{DEFMACRO-BLOCK-SCOPE:EXCLUDES-BINDINGS}
(but not the \param{lambda-list})
\endissue{DEFMACRO-BLOCK-SCOPE:EXCLUDES-BINDINGS}
is
\issue{FLET-IMPLICIT-BLOCK:YES}
implicitly enclosed in a \term{block} named \param{name},
\endissue{FLET-IMPLICIT-BLOCK:YES}
and is evaluated as an \term{implicit progn}, 
returning a new \term{type specifier}.

\issue{DEFINING-MACROS-NON-TOP-LEVEL:ALLOW}
The \term{lexical environment} of the body is the one which was current
at the time the \macref{deftype} form was evaluated, augmented by the 
\term{variables} in the \param{lambda-list}.
\endissue{DEFINING-MACROS-NON-TOP-LEVEL:ALLOW}

\issue{RECURSIVE-DEFTYPE:EXPLICITLY-VAGUE}
Recursive expansion of the \term{type specifier} returned as the expansion
must terminate, including the expansion of \term{type specifiers} which
are nested within the expansion.

The consequences are undefined if the result of fully expanding a
\term{type specifier} contains any circular structure, except within
the \term{objects} referred to by \typeref{member} and \typeref{eql}
\term{type specifiers}.
\endissue{RECURSIVE-DEFTYPE:EXPLICITLY-VAGUE}

%% 4.7.0 4
\param{Documentation} is attached to \param{name} as a \term{documentation string}
of kind \misc{type}.

\issue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY}
% added qualification about top-level-ness  --sjl 5 Mar 92
If a \macref{deftype} \term{form} appears as a \term{top level form},
the \term{compiler} must ensure that the \param{name} is recognized
in subsequent \term{type} declarations.  
The \term{programmer} must ensure that the body of a \macref{deftype} form 
can be \term{evaluated} at compile time if the \param{name} is
referenced in subsequent \term{type} declarations.  
If the expansion of a \term{type specifier} is not defined fully at compile time
(perhaps because it expands into an unknown \term{type specifier} or a
\declref{satisfies} of a named \term{function} that isn't defined in the
compile-time environment), an \term{implementation} may ignore any references to
this \term{type} in declarations and/or signal a warning.
\endissue{COMPILE-FILE-HANDLING-OF-TOP-LEVEL-FORMS:CLARIFY}

\label Examples::
%% 4.7.0 5
\code
 (defun equidimensional (a)
   (or (< (array-rank a) 2)
       (apply #'= (array-dimensions a)))) \EV EQUIDIMENSIONAL
 (deftype square-matrix (&optional type size)
   `(and (array ,type (,size ,size))
         (satisfies equidimensional))) \EV SQUARE-MATRIX
\endcode

\label Side Effects:\None.

\label Affected By:\None.

\label Exceptional Situations:\None.

% addressed in the packages chapter.  --sjl 5 Mar 92
%\issue{LISP-SYMBOL-REDEFINITION:MAR89-X3J13}
%The consequences are undefined if a \term{symbol} in \thepackage{common-lisp}
%is used as the \param{name} argument.
%\endissue{LISP-SYMBOL-REDEFINITION:MAR89-X3J13}

\label See Also::

\misc{declare},
\macref{defmacro},
\funref{documentation},
{\secref\TypeSpecifiers},
{\secref\DocVsDecls}

\label Notes:\None.

\endissue{DECLS-AND-DOC}

\endcom

%%% ========== SUBTYPEP
\begincom{subtypep}\ftype{Function}

\issue{SUBTYPEP-ENVIRONMENT:ADD-ARG}

\label Syntax::

\DefunWithValues subtypep 
		 {type-1 type-2 {\opt} environment}
		 {subtype-p, valid-p}

\label Arguments and Values:: 

\param{type-1}---a \term{type specifier}.
% acceptable to \funref{typep}

\param{type-2}---a \term{type specifier}.
% acceptable to \funref{typep}.

%!!! as opposed to what? need a glossary term -kmp 15-Feb-91

\param{environment}---an \term{environment} \term{object}.
  \Default{\nil, denoting the \term{null lexical environment}
	   and the current \term{global environment}}
%!!! Need to say what happens with the environment.

\param{subtype-p}---a \term{generalized boolean}.

\param{valid-p}---a \term{generalized boolean}.

\label Description::

%% 6.2.1 3
If \param{type-1} is a \term{recognizable subtype} of \param{type-2}, 
the first \term{value} is \term{true}.
Otherwise, the first \term{value} is \term{false},
indicating that either
 \param{type-1} is not a \term{subtype} of \param{type-2}, or else
 \param{type-1} is a \term{subtype} of \param{type-2} 
  but is not a \term{recognizable subtype}.

A second \term{value} is also returned indicating the `certainty' of 
the first \term{value}.  If this value is \term{true}, then the first
value is an accurate indication of the \term{subtype} relationship.
(The second \term{value} is always \term{true} when the first \term{value}
 is \term{true}.)

\Thenextfigure\ summarizes the possible combinations of \term{values}
that might result.

\tablefigthree{Result possibilities for subtypep}{Value 1}{Value 2}{Meaning}{
\term{true}  & \term{true}  & \param{type-1} is definitely a \term{subtype} of
			      \param{type-2}.\cr
\term{false} & \term{true}  & \param{type-1} is definitely not a \term{subtype} of
			      \param{type-2}.\cr
\term{false} & \term{false} & \funref{subtypep} could not determine the relationship,\cr
	     & 	            & so \param{type-1} might or might not be a \term{subtype} of
			      \param{type-2}.\cr
}

\issue{SUBTYPEP-TOO-VAGUE:CLARIFY-MORE}

\funref{subtypep} is permitted to return the 
\term{values} \term{false} and \term{false} only when at least
one argument involves one of these \term{type specifiers}:
  \declref{and},
% Added per Barrett:
  \declref{eql},
  the list form of \declref{function},
  \declref{member},
  \declref{not},
  \declref{or},
  \declref{satisfies},
or
  \declref{values}.
(A \term{type specifier} `involves' such a \term{symbol} if, 
 after being \term{type expanded},
 it contains that \term{symbol} in a position that would call for
 its meaning as a \term{type specifier} to be used.)
One consequence of this is that if neither \param{type-1} nor \param{type-2}
involves any of these \term{type specifiers}, then \funref{subtypep} is obliged
to determine the relationship accurately.  In particular, \funref{subtypep} 
returns the \term{values} \term{true} and \term{true}
if the arguments are \funref{equal} and do not involve
any of these \term{type specifiers}.

\funref{subtypep} never returns a second value of \nil\ when both
\param{type-1} and \param{type-2} involve only
 the names in \figref\StandardizedAtomicTypeSpecs, or
 names of \term{types} defined by \macref{defstruct},
\macref{define-condition},
 or \macref{defclass}, or
 \term{derived types} that expand into only those names.
While \term{type specifiers} listed in \figref\StandardizedAtomicTypeSpecs\ and 
names of \macref{defclass} and \macref{defstruct} can in some cases be
implemented as \term{derived types}, \funref{subtypep} regards them as primitive.

The relationships between \term{types} reflected by \funref{subtypep}
are those specific to the particular implementation.  For example, if
an implementation supports only a single type of floating-point numbers,
in that implementation \f{(subtypep 'float 'long-float)} 
returns the \term{values} \term{true} and \term{true} 
(since the two \term{types} are identical).
\endissue{SUBTYPEP-TOO-VAGUE:CLARIFY-MORE}

\issue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
For all \param{T1} and \param{T2} other than \f{*}, 
\f{(array \param{T1})} and \f{(array \param{T2})} 
are two different \term{type specifiers} that always refer to the same sets of
things if and only if they refer to \term{arrays}
of exactly the same specialized representation, \ie
if \f{(upgraded-array-element-type '\param{T1})}  and
   \f{(upgraded-array-element-type '\param{T2})} 
return two different \term{type specifiers} that always refer to the same sets of
\term{objects}.
This is another way of saying that 
\f{`(array \param{type-specifier})}
and
\f{`(array ,(upgraded-array-element-type '\param{type-specifier}))} 
refer to the same
set of specialized \term{array} representations.
For all \param{T1} and \param{T2} other than \f{*}, 
%tweaked --sjl 7 Mar 92
%the specified intersection for 
%    \f{(array \param{T1})}
%and \f{(array \param{T2})} is \nil\
the intersection of
    \f{(array \param{T1})}
and \f{(array \param{T2})} is the empty set
if and only if they refer to \term{arrays} of different,
distinct specialized representations.  

Therefore,

\code
 (subtypep '(array T1) '(array T2)) \EV \term{true}
\endcode
if and only if

\code
 (upgraded-array-element-type 'T1)  and
 (upgraded-array-element-type 'T2)  
\endcode

return two different \term{type specifiers} that always refer to the same sets of
\term{objects}.
 
For all type-specifiers \param{T1} and \param{T2} other than \f{*}, 

\code
 (subtypep '(complex T1) '(complex T2)) \EV \term{true}, \term{true}
\endcode

if:
\beginlist
\itemitem{1.} \f{T1} is a \term{subtype} of \f{T2}, or
\itemitem{2.} \f{(upgraded-complex-part-type '\param{T1})} and
	      \f{(upgraded-complex-part-type '\param{T2})} 
   return two different \term{type specifiers} that always refer to the 
   same sets of \term{objects}; in this case,
    \f{(complex \param{T1})} and 
    \f{(complex \param{T2})} both refer to the 
   same specialized representation.
\endlist 
The \term{values} are \term{false} and \term{true} otherwise.

The form

\code
 (subtypep '(complex single-float) '(complex float))
\endcode
 must return \term{true} in all implementations, but

\code
 (subtypep '(array single-float) '(array float))
\endcode

returns \term{true} only in implementations that do not have a specialized \term{array}
representation for \term{single floats} distinct from that for other \term{floats}.

\endissue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
 
%% KAB: What??
% When a type description is restricted by range or enumeration, and the
% restricted type is empty.

\label Examples::

\code
 (subtypep 'compiled-function 'function) \EV \term{true}, \term{true}
 (subtypep 'null 'list) \EV \term{true}, \term{true}
 (subtypep 'null 'symbol) \EV \term{true}, \term{true}
 (subtypep 'integer 'string) \EV \term{false}, \term{true}
 (subtypep '(satisfies dummy) nil) \EV \term{false}, \term{implementation-dependent}
 (subtypep '(integer 1 3) '(integer 1 4)) \EV \term{true}, \term{true}
 (subtypep '(integer (0) (0)) 'nil) \EV \term{true}, \term{true}
 (subtypep 'nil '(integer (0) (0))) \EV \term{true}, \term{true}
 (subtypep '(integer (0) (0)) '(member)) \EV \term{true}, \term{true} ;or \term{false}, \term{false}
 (subtypep '(member) 'nil) \EV \term{true}, \term{true} ;or \term{false}, \term{false}
 (subtypep 'nil '(member)) \EV \term{true}, \term{true} ;or \term{false}, \term{false}
\endcode

\issue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
 Let \f{<aet-x>} and \f{<aet-y>} be two distinct \term{type specifiers} that 
do not always refer to the same sets of
\term{objects}
in a given implementation, but for which
\funref{make-array}, will return an 
\term{object} of the same \term{array} \term{type}.
 
Thus, in each case, 
 
\code
  (subtypep (array-element-type (make-array 0 :element-type '<aet-x>))
            (array-element-type (make-array 0 :element-type '<aet-y>)))
\EV \term{true}, \term{true}
 
  (subtypep (array-element-type (make-array 0 :element-type '<aet-y>))
            (array-element-type (make-array 0 :element-type '<aet-x>)))
\EV \term{true}, \term{true}
\endcode
\endissue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
 
If  \f{(array <aet-x>)} 
and \f{(array <aet-y>)} are different names for
exactly the same set of \term{objects}, 
these names should always refer to the same sets of
\term{objects}.
 That implies that the following set of tests are also true:
 
\code
 (subtypep '(array <aet-x>) '(array <aet-y>)) \EV \term{true}, \term{true}
 (subtypep '(array <aet-y>) '(array <aet-x>)) \EV \term{true}, \term{true}
\endcode
 
\label Side Effects:\None.

\label Affected By:\None.

\label Exceptional Situations:\None.

\label See Also::

{\secref\Types}

\label Notes::

\issue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
The small differences between the \funref{subtypep} specification for
the \typeref{array} and \typeref{complex} types are necessary because there 
is no creation function for \term{complexes} which allows 
the specification of the resultant part type independently of
the actual types of the parts.  Thus in the case of \thetype{complex},
the actual type of the parts is referred to, although a \term{number} 
can be a member of more than one \term{type}.
For example, \f{17} is of \term{type} \f{(mod 18)} 
as well as \term{type} \f{(mod 256)} and \term{type} \typeref{integer};
and \f{2.3f5} is \oftype{single-float} 
as well as \term{type} \typeref{float}.
\endissue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
 
\endissue{SUBTYPEP-ENVIRONMENT:ADD-ARG}

\endcom

%%% ========== TYPE-OF
\begincom{type-of}\ftype{Function}

\label Syntax::

\DefunWithValues type-of {object} {typespec}

\label Arguments and Values::

\param{object}---an \term{object}.

\param{typespec}---a \term{type specifier}.

\label Description::

\issue{TYPE-OF-UNDERCONSTRAINED:ADD-CONSTRAINTS}
 
Returns a \term{type specifier}, \param{typespec}, for a \term{type} 
that has the \param{object} as an \term{element}.
The \param{typespec} satisfies the following:

\beginlist

\itemitem{1.}
For any \param{object} that is an \term{element} of some \term{built-in type}:

\beginlist
\itemitem{a.}
the \term{type} returned is a \term{recognizable subtype} of that \term{built-in type}.

\itemitem{b.}
%KMP: I added MEMBER and EQL because they seemed to be missing only by accident.
%     The discussion of TYPE-OF-UNDERCONSTRAINED seems to imply that MEMBER
%     is missing due to editing error. And I think EQL was added later. -kmp 3-Jun-91
the \term{type} returned does not involve 
     \f{and},
     \f{eql},
     \f{member},
     \f{not},
     \f{or}, 
     \f{satisfies},
  or \f{values}.
\endlist

\itemitem{2.}
For all \param{objects}, \f{(typep \param{object} (type-of \param{object}))} 
returns \term{true}.
%Per Barmar:
Implicit in this is that \term{type specifiers} which are
not valid for use with \funref{typep}, such as the \term{list} form of the
\funref{function} \term{type specifier}, are never returned by \funref{type-of}.

\itemitem{3.}
The \term{type} returned by \funref{type-of} is always a \term{recognizable subtype}
of the \term{class} returned by \funref{class-of}.  That is,

\code
 (subtypep (type-of \param{object}) (class-of \param{object})) \EV \term{true}, \term{true}
\endcode

\itemitem{4.}
For \param{objects} of metaclass \typeref{structure-class} or \typeref{standard-class},
\issue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
and for \term{conditions},
\endissue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\funref{type-of} returns the \term{proper name} of the \term{class} returned 
by \funref{class-of} if it has a \term{proper name},
and otherwise returns the \term{class} itself.
In particular, for \param{objects} created by the constructor function
of a structure defined with \macref{defstruct} without a \kwd{type} option,
\funref{type-of} returns the structure name; and for \param{objects} created 
by \funref{make-condition}, the \param{typespec} is the \term{name} of the
\term{condition} \term{type}.
 
\issue{TYPE-OF-AND-PREDEFINED-CLASSES:TYPE-OF-HANDLES-FLOATS}
\itemitem{5.}
For each of the \term{types}
     \typeref{short-float}, 
     \typeref{single-float},
     \typeref{double-float},
  or \typeref{long-float}
of which the \param{object} is an \term{element},
the \param{typespec} is a \term{recognizable subtype} of that \term{type}.
\endissue{TYPE-OF-AND-PREDEFINED-CLASSES:TYPE-OF-HANDLES-FLOATS}

\endlist

\endissue{TYPE-OF-UNDERCONSTRAINED:ADD-CONSTRAINTS}
 
%(The CLOS specification has already specified that class objects are
%acceptable wherever \term{type specifiers} are, and in particular, as input to
%SUBTYPEP and TYPEP.)
% 
%This proposal is intended to be consistent with 88-002R, 
%and not to conflict with any of the definitions in that document.

%If \param{object} is not a user-defined named
%\term{structure} 
%created by \macref{defstruct}, 
%\funref{type-of} returns a \term{type} of which 
%\param{object} 
%is a member.
%%% 4.9.0 3
%The result in this case is \term{implementation-dependent}.
%For example:
%
%\code
% (type-of "abc") \EV SIMPLE-STRING
% (type-of "abc") \EV STRING
% (type-of "abc") \EV ARRAY
%\endcode
%If \param{object} is a user-defined named
%\term{structure} 
%created by \macref{defstruct}, then \funref{type-of} 
%returns the type name
%of that \term{structure}.

\label Examples::

\code
\endcode

\issue{TYPE-OF-UNDERCONSTRAINED:ADD-CONSTRAINTS}
\code
 (type-of 'a) \EV SYMBOL          
 (type-of '(1 . 2))
\EV CONS
\OV (CONS FIXNUM FIXNUM)
 (type-of #c(0 1))
\EV COMPLEX
\OV (COMPLEX INTEGER)
 (defstruct temp-struct x y z) \EV TEMP-STRUCT
 (type-of (make-temp-struct)) \EV TEMP-STRUCT
 (type-of "abc")
\EV STRING
\OV (STRING 3)
 (subtypep (type-of "abc") 'string) \EV \term{true}, \term{true}
 (type-of (expt 2 40))
\EV BIGNUM
\OV INTEGER
\OV (INTEGER 1099511627776 1099511627776)
\OV SYSTEM::TWO-WORD-BIGNUM
\OV FIXNUM
 (subtypep (type-of 112312) 'integer) \EV \term{true}, \term{true}
 (defvar *foo* (make-array 5 :element-type t)) \EV *FOO*
 (class-name (class-of *foo*)) \EV VECTOR
 (type-of *foo*)
\EV VECTOR
\OV (VECTOR T 5)
\endcode
\endissue{TYPE-OF-UNDERCONSTRAINED:ADD-CONSTRAINTS}

\label Affected By:\None.

\label Exceptional Situations:\None!

\label See Also::

\funref{array-element-type},
\funref{class-of},
\macref{defstruct},
\macref{typecase},
\funref{typep},
{\secref\Types}

\label Notes::

Implementors are encouraged to arrange for \funref{type-of} to return
\issue{TYPE-OF-UNDERCONSTRAINED:ADD-CONSTRAINTS}
%the most specific \term{type} that can be conveniently computed and
%is likely to be useful to the user.
a portable value.
%Barmar: "a type specifier defined in this standard"
%KMP: This is a little messy. The problem is that user-defined types are
%     not directly described here,...
\endissue{TYPE-OF-UNDERCONSTRAINED:ADD-CONSTRAINTS}
 
\endcom

%%% ========== TYPEP
\begincom{typep}\ftype{Function}

\issue{SUBTYPEP-ENVIRONMENT:ADD-ARG}

\label Syntax::

\DefunWithValues typep {object type-specifier {\opt} environment} {generalized-boolean}
                                    
\label Arguments and Values::

\param{object}---an \term{object}.

\param{type-specifier}---any \term{type specifier} except 
\issue{FUNCTION-TYPE}%
% The following will be deleted from the standard:
% 
% \declref{function},
\endissue{FUNCTION-TYPE}%
\misc{values}, or a \term{type specifier} list
whose first element is either \misc{function} or \misc{values}.

\param{environment}---an \term{environment} \term{object}.
  \Default{\nil, denoting the \term{null lexical environment}
	   and the and current \term{global environment}}
%!!! Need to say what happens with the environment.

\param{generalized-boolean}---a \term{generalized boolean}.

\label Description::

%% 6.2.1 2
\Predicate{object}{of the \term{type} specified by \param{type-specifier}}

% already stated elsewhere, not crucial here.  --sjl 7 Mar 92
%\param{Object} can be of more than one \term{type},
%since one \term{type} can include another.  
A \param{type-specifier} of the form \f{(satisfies fn)} 
is handled by applying the function \f{fn} to \param{object}.

\issue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
\f{(typep \param{object} '(array \param{type-specifier}))}, 
where \param{type-specifier} is not \f{*},   
returns \term{true} if and only if \param{object} is an \term{array} 
that could be the result 
of supplying \param{type-specifier} 
as the \kwd{element-type} argument to \funref{make-array}.
\f{(array *)} refers to all \term{arrays} 
regardless of element type, while \f{(array \param{type-specifier})}
refers only to those \term{arrays} 
that can result from giving \param{type-specifier} as the
\kwd{element-type} argument to \funref{make-array}.  
A similar interpretation applies to \f{(simple-array \param{type-specifier})} 
and \f{(vector \param{type-specifier})}.
\Seesection\ArrayUpgrading.

\f{(typep \param{object} '(complex \param{type-specifier}))}
returns \term{true} for all \term{complex} numbers that can result from 
giving \term{numbers} of type \param{type-specifier}
to \thefunction{complex}, plus all other \term{complex} numbers 
of the same specialized representation.      
Both the real and the imaginary parts of any such 
\term{complex} number must satisfy:

\code
 (typep realpart 'type-specifier)
 (typep imagpart 'type-specifier)
\endcode
 
\Seefun{upgraded-complex-part-type}.

\endissue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}

\label Examples::

\code
 (typep 12 'integer) \EV \term{true}
 (typep (1+ most-positive-fixnum) 'fixnum) \EV \term{false}
 (typep nil t) \EV \term{true}
 (typep nil nil) \EV \term{false}
 (typep 1 '(mod 2)) \EV \term{true}
 (typep #c(1 1) '(complex (eql 1))) \EV \term{true}
;; To understand this next example, you might need to refer to
;; \secref\RuleOfCanonRepForComplexRationals.
 (typep #c(0 0) '(complex (eql 0))) \EV \term{false}
\endcode

\issue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
Let \f{A\sssx} and \f{A\sssy} be two \term{type specifiers} that 
denote different \term{types}, but for which

\code
 (upgraded-array-element-type 'A\sssx)
\endcode
and

\code
 (upgraded-array-element-type 'A\sssy)
\endcode
denote the same \term{type}.  Notice that
 
\code
 (typep (make-array 0 :element-type 'A\sssx) '(array A\sssx)) \EV \term{true}
 (typep (make-array 0 :element-type 'A\sssy) '(array A\sssy)) \EV \term{true}
 (typep (make-array 0 :element-type 'A\sssx) '(array A\sssy)) \EV \term{true}
 (typep (make-array 0 :element-type 'A\sssy) '(array A\sssx)) \EV \term{true}
\endcode

\endissue{ARRAY-TYPE-ELEMENT-TYPE-SEMANTICS:UNIFY-UPGRADING}
 
\label Affected By:\None.

\label Exceptional Situations::

%% 4.5.0.0 10
An error \oftype{error} is signaled if \param{type-specifier} is \f{values}, 
or a \term{type specifier} list whose first element is either
\misc{function} or \misc{values}.

The consequences are undefined if
the \param{type-specifier} is not a \term{type specifier}.

\label See Also::

\funref{type-of},
\funref{upgraded-array-element-type},
\funref{upgraded-complex-part-type},
{\secref\TypeSpecifiers}

\label Notes::

\term{Implementations} are encouraged to recognize and optimize the case of 
\f{(typep \param{x} (the class \param{y}))},
since it does not involve any need for expansion 
of \macref{deftype} information at runtime.

\code

\endcode

\endissue{SUBTYPEP-ENVIRONMENT:ADD-ARG}

\endcom

%-------------------- Type Errors --------------------

\begincom{type-error}\ftype{Condition Type}

\label Class Precedence List::
\typeref{type-error},
\typeref{error},
\typeref{serious-condition},
\typeref{condition},
\typeref{t}

\label Description::

\Thetype{type-error} represents a situation in which an \term{object} is not
of the expected type.  The ``offending datum'' and ``expected type'' are initialized 
by \theinitkeyargs{datum} and \kwd{expected-type} to \funref{make-condition},
and are \term{accessed} by the functions 
\funref{type-error-datum} and \funref{type-error-expected-type}.

\label See Also::

\funref{type-error-datum}, \funref{type-error-expected-type}

\endcom%{type-error}\ftype{Condition Type}

%%% ========== TYPE-ERROR-DATUM
\begincom{type-error-datum, type-error-expected-type}\ftype{Function}

\label Syntax::

\DefunWithValues type-error-datum {condition} {datum}
\DefunWithValues type-error-expected-type {condition} {expected-type}

\label Arguments and Values:: 

\param{condition}---a \term{condition} \oftype{type-error}.

\param{datum}---an \term{object}.

\param{expected-type}---a \term{type specifier}.

\label Description::

\funref{type-error-datum} returns the offending datum in the \term{situation}
represented by the \param{condition}.

\funref{type-error-expected-type} returns the expected type of the
offending datum in the \term{situation} represented by the \param{condition}.

\label Examples::

\code
 (defun fix-digits (condition)
   (check-type condition type-error)
   (let* ((digits '(zero one two three four
                   five six seven eight nine))
         (val (position (type-error-datum condition) digits)))
     (if (and val (subtypep 'fixnum (type-error-expected-type condition)))
         (store-value 7))))
 
 (defun foo (x)
   (handler-bind ((type-error #'fix-digits))
     (check-type x number)
     (+ x 3)))
 
 (foo 'seven)
\EV 10
\endcode

\label Side Effects:\None.

\label Affected By:\None.

\label Exceptional Situations:\None.

\label See Also::

\typeref{type-error},
{\secref\Conditions}

\label Notes:\None.

%% Shouldn't be needed. -kmp 1-Sep-91
%It is an error to use \macref{setf} with \funref{type-error-datum}.
%It is an error to use \macref{setf} with \funref{type-error-expected-type}.

\endcom

%%% ========== SIMPLE-TYPE-ERROR

\begincom{simple-type-error}\ftype{Condition Type}

\label Class Precedence List::

\issue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}
\typeref{simple-type-error},
\typeref{simple-condition},
\typeref{type-error},
\typeref{error},
\typeref{serious-condition},
\typeref{condition},
\typeref{t}
\endissue{TYPE-OF-AND-PREDEFINED-CLASSES:UNIFY-AND-EXTEND}

\label Description::

\term{Conditions} \oftype{simple-type-error} 
are like \term{conditions} \oftype{type-error}, 
except that they provide an alternate mechanism for specifying
how the \term{condition} is to be \term{reported};
\seetype{simple-condition}.

\label See Also::

\typeref{simple-condition},
\issue{FORMAT-STRING-ARGUMENTS:SPECIFY}
\funref{simple-condition-format-control},
\endissue{FORMAT-STRING-ARGUMENTS:SPECIFY}
\funref{simple-condition-format-arguments}, 
\funref{type-error-datum},
\funref{type-error-expected-type}

\endcom%{simple-type-error}\ftype{Condition Type}
