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; Introduce type specifiers to the elisp manual (bug#73626)

* doc/lispref/objects.texi (Programming Types): Add 'Type Specifiers' entry.
(Type Specifiers): Add node.
* doc/lispref/functions.texi (Declare Form): Add 'Type Specifiers'
reference.
This commit is contained in:
Andrea Corallo 2024-11-14 00:20:13 +01:00
parent 83fc3cf53a
commit 59b3eae481
2 changed files with 92 additions and 4 deletions

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@ -2733,10 +2733,11 @@ native compiler (@pxref{Native Compilation}) for improving code
generation and for deriving more precisely the type of other functions
without type declaration.
@var{type} is a type specifier in the form @w{@code{(function
(ARG-1-TYPE ... ARG-N-TYPE) RETURN-TYPE)}}. Argument types can be
interleaved with symbols @code{&optional} and @code{&rest} to match the
function's arguments (@pxref{Argument List}).
@var{type} is a @dfn{type specifier} (@pxref{Type Specifiers}) in the
form @w{@code{(function (@var{arg-1-type} ... @var{arg-n-type})
RETURN-TYPE)}}. Argument types can be interleaved with symbols
@code{&optional} and @code{&rest} to match the function's arguments
(@pxref{Argument List}).
@var{function} if present should be the name of function being defined.

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@ -247,6 +247,7 @@ latter are unique to Emacs Lisp.
* Closure Type:: A function written in Lisp.
* Record Type:: Compound objects with programmer-defined types.
* Type Descriptors:: Objects holding information about types.
* Type Specifiers:: Expressions which describe types.
* Autoload Type:: A type used for automatically loading seldom-used
functions.
* Finalizer Type:: Runs code when no longer reachable.
@ -1499,6 +1500,92 @@ free for use by Lisp extensions.
An example of a type descriptor is any instance of
@code{cl-structure-class}.
@node Type Specifiers
@subsection Type Specifiers
@cindex type specifier
A type specifier is an expression that denotes a type. A type
represents a set of possible values. Type specifiers can be classified
in primitives and compounds.
Type specifiers are in use for several purposes including: documenting
function interfaces through declaration (@pxref{Declare Form}),
specifying structure slot values (@pxref{Structures,,, cl, Common Lisp
Extensions for GNU Emacs Lisp}), type-checking through @code{cl-the}
(@pxref{Declarations,,, cl, Common Lisp Extensions for GNU Emacs Lisp})
and others.
@table @asis
@item Primitive type specifiers
Primitive types specifiers are the basic types (i.e.@: not composed by other
type specifiers).
Built-in primitive types (like @code{integer}, @code{float},
@code{string} etc) are listed in @ref{Type Hierarchy}.
@item Compound type specifiers
Compound types serve the purpose of defining more complex or precise
type specifications by combining or modifying simpler types.
List of compound type specifiers:
@table @code
@item (or @var{type-1} .. @var{type-n})
The @code{or} type specifier describes a type that satisfies at least
one of the given types.
@item (and @var{type-1} .. @var{type-n})
Similarly the @code{and} type specifier describes a type that satisfies
all the given types.
@item (not @var{type})
The @code{not} type specifier defines any type except the specified one.
@item (member @var{value-1} .. @var{value-n})
The @code{member} type specifier allows to specify a type that includes
only the explicitly listed values.
@item (function (@var{arg-1-type} ... @var{arg-n-type}) @var{return-type})
The @code{function} type specifier is used to describe the argument
types and return type of a function. Argument types can be interleaved
with symbols @code{&optional} and @code{&rest} to match the function's
arguments (@pxref{Argument List}).
The following is to represent a function with: a first parameter of type
@code{symbol}, a second optional parameter of type @code{float} and
returning an @code{integer}:
@example
(function (symbol &optional float) integer)
@end example
@item (integer @var{lower-bound} @var{upper-bound})
@code{integer} can be used as well as a compound type specifier to
define a subset of integers by specifying a range. This allows to
precisely control which integers are valid for a given type.
@var{lower-bound} is the minimum integer value in the range and
@var{upper-bound} the maximum. It is possible to use @code{*} to
indicate no lower or uper limit.
The following represents all integers from -10 to 10.
@example
(integer -10 10)
@end example
The following represents 10.
@example
(integer 10 10)
@end example
The following represents all integers from negative infinity to 10.
@example
(integer * 10)
@end example
@end table
@end table
@node Autoload Type
@subsection Autoload Type