@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
-@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2007, 2008, 2009, 2010, 2011
+@c Copyright (C) 1996, 1997, 2000-2004, 2007-2014
@c Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.
* General Information about Modules:: Guile module basics.
* Using Guile Modules:: How to use existing modules.
* Creating Guile Modules:: How to package your code into modules.
-* Module System Reflection:: Accessing module objects at run-time.
-* Included Guile Modules:: Which modules come with Guile?
+* Modules and the File System:: Installing modules in the file system.
* R6RS Version References:: Using version numbers with modules.
* R6RS Libraries:: The library and import forms.
-* Accessing Modules from C:: How to work with modules with C code.
* Variables:: First-class variables.
+* Module System Reflection:: First-class modules.
+* Accessing Modules from C:: How to work with modules with C code.
* provide and require:: The SLIB feature mechanism.
* Environments:: R5RS top-level environments.
@end menu
variables and macros. More precisely, it is a set of @dfn{bindings}
of symbols (names) to Scheme objects.
-An environment is a mapping from identifiers (or symbols) to locations,
-i.e., a set of bindings.
-There are top-level environments and lexical environments.
-The environment in which a lambda is executed is remembered as part of its
-definition.
-
Within a module, all bindings are visible. Certain bindings
can be declared @dfn{public}, in which case they are added to the
module's so-called @dfn{export list}; this set of public bindings is
providing module's public interface, the entire export list is available
without renaming (@pxref{Using Guile Modules}).
-To use a module, it must be found and loaded. All Guile modules have a
-unique @dfn{module name}, which is a list of one or more symbols.
-Examples are @code{(ice-9 popen)} or @code{(srfi srfi-11)}. When Guile
-searches for the code of a module, it constructs the name of the file to
-load by concatenating the name elements with slashes between the
-elements and appending a number of file name extensions from the list
-@code{%load-extensions} (@pxref{Loading}). The resulting file name is
-then searched in all directories in the variable @code{%load-path}
-(@pxref{Build Config}). For example, the @code{(ice-9 popen)} module
-would result in the filename @code{ice-9/popen.scm} and searched in the
-installation directories of Guile and in all other directories in the
-load path.
-
-A slightly different search mechanism is used when a client module
-specifies a version reference as part of a request to load a module
-(@pxref{R6RS Version References}). Instead of searching the directories
-in the load path for a single filename, Guile uses the elements of the
-version reference to locate matching, numbered subdirectories of a
-constructed base path. For example, a request for the
-@code{(rnrs base)} module with version reference @code{(6)} would cause
-Guile to discover the @code{rnrs/6} subdirectory (if it exists in any of
-the directories in the load path) and search its contents for the
-filename @code{base.scm}.
-
-When multiple modules are found that match a version reference, Guile
-sorts these modules by version number, followed by the length of their
-version specifications, in order to choose a ``best'' match.
-
-@c FIXME::martin: Not sure about this, maybe someone knows better?
-Every module has a so-called syntax transformer associated with it.
-This is a procedure which performs all syntax transformation for the
-time the module is read in and evaluated. When working with modules,
-you can manipulate the current syntax transformer using the
-@code{use-syntax} syntactic form or the @code{#:use-syntax} module
-definition option (@pxref{Creating Guile Modules}).
+All Guile modules have a unique @dfn{module name}, for example
+@code{(ice-9 popen)} or @code{(srfi srfi-11)}. Module names are lists
+of one or more symbols.
+When Guile goes to use an interface from a module, for example
+@code{(ice-9 popen)}, Guile first looks to see if it has loaded
+@code{(ice-9 popen)} for any reason. If the module has not been loaded
+yet, Guile searches a @dfn{load path} for a file that might define it,
+and loads that file.
+
+The following subsections go into more detail on using, creating,
+installing, and otherwise manipulating modules and the module system.
@node Using Guile Modules
@subsection Using Guile Modules
which accepts one or more interface specifications and, upon evaluation,
arranges for those interfaces to be available to the current module.
This process may include locating and loading code for a given module if
-that code has not yet been loaded, following @code{%load-path} (@pxref{Build
-Config}).
+that code has not yet been loaded, following @code{%load-path}
+(@pxref{Modules and the File System}).
An @dfn{interface specification} has one of two forms. The first
variation is simply to name the module, in which case its public
Here, the interface specification is @code{(ice-9 popen)}, and the
result is that the current module now has access to @code{open-pipe},
-@code{close-pipe}, @code{open-input-pipe}, and so on (@pxref{Included
-Guile Modules}).
+@code{close-pipe}, @code{open-input-pipe}, and so on (@pxref{Pipes}).
Note in the previous example that if the current module had already
defined @code{open-pipe}, that definition would be overwritten by the
#:renamer (symbol-prefix-proc 'unixy:)))
@end lisp
+@noindent
+or more simply:
+
+@cindex prefix
+@lisp
+(use-modules ((ice-9 popen)
+ #:select ((open-pipe . pipe-open) close-pipe)
+ #:prefix unixy:))
+@end lisp
+
Here, the interface specification is more complex than before, and the
result is that a custom interface with only two bindings is created and
subsequently accessed by the current module. The mapping of old to new
You can also use the @code{@@} and @code{@@@@} syntaxes as the target
of a @code{set!} when the binding refers to a variable.
-@c begin (scm-doc-string "boot-9.scm" "symbol-prefix-proc")
@deffn {Scheme Procedure} symbol-prefix-proc prefix-sym
Return a procedure that prefixes its arg (a symbol) with
@var{prefix-sym}.
-@c Insert gratuitous C++ slam here. --ttn
@end deffn
-@c begin (scm-doc-string "boot-9.scm" "use-modules")
@deffn syntax use-modules spec @dots{}
Resolve each interface specification @var{spec} into an interface and
arrange for these to be accessible by the current module. The return
@cindex binding renamer
@lisp
- (MODULE-NAME [:select SELECTION] [:renamer RENAMER])
+ (MODULE-NAME [#:select SELECTION]
+ [#:prefix PREFIX]
+ [#:renamer RENAMER])
@end lisp
in which case a custom interface is newly created and used.
@var{module-name} is a list of symbols, as above; @var{selection} is a
-list of selection-specs; and @var{renamer} is a procedure that takes a
-symbol and returns its new name. A selection-spec is either a symbol or
-a pair of symbols @code{(ORIG . SEEN)}, where @var{orig} is the name in
-the used module and @var{seen} is the name in the using module. Note
-that @var{seen} is also passed through @var{renamer}.
-
-The @code{:select} and @code{:renamer} clauses are optional. If both are
-omitted, the returned interface has no bindings. If the @code{:select}
-clause is omitted, @var{renamer} operates on the used module's public
-interface.
-
-In addition to the above, @var{spec} can also include a @code{:version}
+list of selection-specs; @var{prefix} is a symbol that is prepended to
+imported names; and @var{renamer} is a procedure that takes a symbol and
+returns its new name. A selection-spec is either a symbol or a pair of
+symbols @code{(ORIG . SEEN)}, where @var{orig} is the name in the used
+module and @var{seen} is the name in the using module. Note that
+@var{seen} is also modified by @var{prefix} and @var{renamer}.
+
+The @code{#:select}, @code{#:prefix}, and @code{#:renamer} clauses are
+optional. If all are omitted, the returned interface has no bindings.
+If the @code{#:select} clause is omitted, @var{prefix} and @var{renamer}
+operate on the used module's public interface.
+
+In addition to the above, @var{spec} can also include a @code{#:version}
clause, of the form:
@lisp
- :version VERSION-SPEC
+ #:version VERSION-SPEC
@end lisp
-where @var{version-spec} is an R6RS-compatible version reference. The
-presence of this clause changes Guile's search behavior as described in
-the section on module name resolution
-(@pxref{General Information about Modules}). An error will be signaled
-in the case in which a module with the same name has already been
-loaded, if that module specifies a version and that version is not
-compatible with @var{version-spec}.
+where @var{version-spec} is an R6RS-compatible version reference. An
+error will be signaled in the case in which a module with the same name
+has already been loaded, if that module specifies a version and that
+version is not compatible with @var{version-spec}. @xref{R6RS Version
+References}, for more on version references.
-Signal error if module name is not resolvable.
-@end deffn
-
-
-@c FIXME::martin: Is this correct, and is there more to say?
-@c FIXME::martin: Define term and concept `syntax transformer' somewhere.
-
-@deffn syntax use-syntax module-name
-Load the module @code{module-name} and use its syntax
-transformer as the syntax transformer for the currently defined module,
-as well as installing it as the current syntax transformer.
+If the module name is not resolvable, @code{use-modules} will signal an
+error.
@end deffn
@deffn syntax @@ module-name binding-name
by using @code{define-public} or @code{export} (both documented below).
@end itemize
-@c begin (scm-doc-string "boot-9.scm" "define-module")
-@deffn syntax define-module module-name [options @dots{}]
-@var{module-name} is of the form @code{(hierarchy file)}. One
-example of this is
+@deffn syntax define-module module-name option @dots{}
+@var{module-name} is a list of one or more symbols.
@lisp
(define-module (ice-9 popen))
@code{define-module} makes this module available to Guile programs under
the given @var{module-name}.
-The @var{options} are keyword/value pairs which specify more about the
-defined module. The recognized options and their meaning is shown in
+@var{option} @dots{} are keyword/value pairs which specify more about the
+defined module. The recognized options and their meaning are shown in
the following table.
-@c fixme: Should we use "#:" or ":"?
-
@table @code
@item #:use-module @var{interface-specification}
Equivalent to a @code{(use-modules @var{interface-specification})}
(@pxref{Using Guile Modules}).
-@item #:use-syntax @var{module}
-Use @var{module} when loading the currently defined module, and install
-it as the syntax transformer.
-
@item #:autoload @var{module} @var{symbol-list}
@cindex autoload
Load @var{module} when any of @var{symbol-list} are accessed. For
@item #:export @var{list}
@cindex export
Export all identifiers in @var{list} which must be a list of symbols
-or pairs of symbols. This is equivalent to @code{(export @var{list})}
+or pairs of symbols. This is equivalent to @code{(export @var{list})}
in the module body.
@item #:re-export @var{list}
imported by the current module from other modules. This is equivalent
to @code{re-export} below.
-@item #:export-syntax @var{list}
-@cindex export-syntax
-Export all identifiers in @var{list} which must be a list of symbols
-or pairs of symbols. The identifiers in @var{list} must refer to
-macros (@pxref{Macros}) defined in the current module. This is
-equivalent to @code{(export-syntax @var{list})} in the module body.
-
-@item #:re-export-syntax @var{list}
-@cindex re-export-syntax
-Re-export all identifiers in @var{list} which must be a list of
-symbols or pairs of symbols. The symbols in @var{list} must refer to
-macros imported by the current module from other modules. This is
-equivalent to @code{(re-export-syntax @var{list})} in the module body.
-
@item #:replace @var{list}
@cindex replace
@cindex replacing binding
knows what she is doing, and uses @code{#:replace} for this binding
rather than @code{#:export}.
+A @code{#:replace} clause is equivalent to @code{(export! @var{list})}
+in the module body.
+
The @code{#:duplicates} (see below) provides fine-grain control about
duplicate binding handling on the module-user side.
policies may explicitly leave the responsibility of handling the
duplication to the next handler in @var{list}.
+If GOOPS has been loaded before the @code{#:duplicates} clause is
+processed, there are additional strategies available for dealing with
+generic functions. @xref{Merging Generics}, for more information.
+
@findex default-duplicate-binding-handler
The default duplicate binding resolution policy is given by the
@code{default-duplicate-binding-handler} procedure, and is
(replace warn-override-core warn last)
@end lisp
-@item #:no-backtrace
-@cindex no backtrace
-Tell Guile not to record information for procedure backtraces when
-executing the procedures in this module.
-
@item #:pure
@cindex pure module
Create a @dfn{pure} module, that is a module which does not contain any
@end table
@end deffn
-@c end
@deffn syntax export variable @dots{}
Add all @var{variable}s (which must be symbols or pairs of symbols) to
the current module's public interface.
@end deffn
-@c begin (scm-doc-string "boot-9.scm" "define-public")
@deffn syntax define-public @dots{}
Equivalent to @code{(begin (define foo ...) (export foo))}.
@end deffn
-@c end
@deffn syntax re-export variable @dots{}
Add all @var{variable}s (which must be symbols or pairs of symbols) to
imported by the current module from some other module.
@end deffn
-@node Module System Reflection
-@subsection Module System Reflection
-
-The previous sections have described a declarative view of the module
-system. You can also work with it programmatically by accessing and
-modifying various parts of the Scheme objects that Guile uses to
-implement the module system.
-
-At any time, there is a @dfn{current module}. This module is the one
-where a top-level @code{define} and similar syntax will add new
-bindings. You can find other module objects with @code{resolve-module},
-for example.
-
-These module objects can be used as the second argument to @code{eval}.
-
-@deffn {Scheme Procedure} current-module
-Return the current module object.
+@deffn syntax export! variable @dots{}
+Like @code{export}, but marking the exported variables as replacing.
+Using a module with replacing bindings will cause any existing bindings
+to be replaced without issuing any warnings. See the discussion of
+@code{#:replace} above.
@end deffn
-@deffn {Scheme Procedure} set-current-module module
-Set the current module to @var{module} and return
-the previous current module.
-@end deffn
-
-@deffn {Scheme Procedure} save-module-excursion thunk
-Call @var{thunk} within a @code{dynamic-wind} such that the module that
-is current at invocation time is restored when @var{thunk}'s dynamic
-extent is left (@pxref{Dynamic Wind}).
-
-More precisely, if @var{thunk} escapes non-locally, the current module
-(at the time of escape) is saved, and the original current module (at
-the time @var{thunk}'s dynamic extent was last entered) is restored. If
-@var{thunk}'s dynamic extent is re-entered, then the current module is
-saved, and the previously saved inner module is set current again.
-@end deffn
-
-@deffn {Scheme Procedure} resolve-module name
-Find the module named @var{name} and return it. When it has not already
-been defined, try to auto-load it. When it can't be found that way
-either, create an empty module. The name is a list of symbols.
-@end deffn
-
-@deffn {Scheme Procedure} resolve-interface name
-Find the module named @var{name} as with @code{resolve-module} and
-return its interface. The interface of a module is also a module
-object, but it contains only the exported bindings.
-@end deffn
-
-@deffn {Scheme Procedure} module-use! module interface
-Add @var{interface} to the front of the use-list of @var{module}. Both
-arguments should be module objects, and @var{interface} should very
-likely be a module returned by @code{resolve-interface}.
-@end deffn
-
-@deffn {Scheme Procedure} reload-module module
-Revisit the source file that corresponds to @var{module}. Raises an
-error if no source file is associated with the given module.
-@end deffn
-
-
-@node Included Guile Modules
-@subsection Included Guile Modules
-
-@c FIXME::martin: Review me!
-
-Some modules are included in the Guile distribution; here are references
-to the entries in this manual which describe them in more detail:
-
-@table @strong
-@item boot-9
-boot-9 is Guile's initialization module, and it is always loaded when
-Guile starts up.
-
-@item (ice-9 expect)
-Actions based on matching input from a port (@pxref{Expect}).
-
-@item (ice-9 format)
-Formatted output in the style of Common Lisp (@pxref{Formatted
-Output}).
-
-@item (ice-9 ftw)
-File tree walker (@pxref{File Tree Walk}).
-
-@item (ice-9 getopt-long)
-Command line option processing (@pxref{getopt-long}).
-
-@item (ice-9 history)
-Refer to previous interactive expressions (@pxref{Value History}).
+@node Modules and the File System
+@subsection Modules and the File System
-@item (ice-9 popen)
-Pipes to and from child processes (@pxref{Pipes}).
+Typical programs only use a small subset of modules installed on a Guile
+system. In order to keep startup time down, Guile only loads modules
+when a program uses them, on demand.
-@item (ice-9 pretty-print)
-Nicely formatted output of Scheme expressions and objects
-(@pxref{Pretty Printing}).
+When a program evaluates @code{(use-modules (ice-9 popen))}, and the
+module is not loaded, Guile searches for a conventionally-named file
+from in the @dfn{load path}.
-@item (ice-9 q)
-First-in first-out queues (@pxref{Queues}).
+In this case, loading @code{(ice-9 popen)} will eventually cause Guile
+to run @code{(primitive-load-path "ice-9/popen")}.
+@code{primitive-load-path} will search for a file @file{ice-9/popen} in
+the @code{%load-path} (@pxref{Load Paths}). For each directory in
+@code{%load-path}, Guile will try to find the file name, concatenated
+with the extensions from @code{%load-extensions}. By default, this will
+cause Guile to @code{stat} @file{ice-9/popen.scm}, and then
+@file{ice-9/popen}. @xref{Load Paths}, for more on
+@code{primitive-load-path}.
-@item (ice-9 rdelim)
-Line- and character-delimited input (@pxref{Line/Delimited}).
+If a corresponding compiled @file{.go} file is found in the
+@code{%load-compiled-path} or in the fallback path, and is as fresh as
+the source file, it will be loaded instead of the source file. If no
+compiled file is found, Guile may try to compile the source file and
+cache away the resulting @file{.go} file. @xref{Compilation}, for more
+on compilation.
-@item (ice-9 readline)
-@code{readline} interactive command line editing (@pxref{Readline
-Support}).
+Once Guile finds a suitable source or compiled file is found, the file
+will be loaded. If, after loading the file, the module under
+consideration is still not defined, Guile will signal an error.
-@item (ice-9 receive)
-Multiple-value handling with @code{receive} (@pxref{Multiple Values}).
-
-@item (ice-9 regex)
-Regular expression matching (@pxref{Regular Expressions}).
-
-@item (ice-9 rw)
-Block string input/output (@pxref{Block Reading and Writing}).
-
-@item (ice-9 streams)
-Sequence of values calculated on-demand (@pxref{Streams}).
-
-@item (ice-9 syncase)
-R5RS @code{syntax-rules} macro system (@pxref{Syntax Rules}).
-
-@item (ice-9 threads)
-Guile's support for multi threaded execution (@pxref{Scheduling}).
-
-@item (ice-9 documentation)
-Online documentation (REFFIXME).
-
-@item (srfi srfi-1)
-A library providing a lot of useful list and pair processing
-procedures (@pxref{SRFI-1}).
-
-@item (srfi srfi-2)
-Support for @code{and-let*} (@pxref{SRFI-2}).
-
-@item (srfi srfi-4)
-Support for homogeneous numeric vectors (@pxref{SRFI-4}).
-
-@item (srfi srfi-6)
-Support for some additional string port procedures (@pxref{SRFI-6}).
-
-@item (srfi srfi-8)
-Multiple-value handling with @code{receive} (@pxref{SRFI-8}).
-
-@item (srfi srfi-9)
-Record definition with @code{define-record-type} (@pxref{SRFI-9}).
-
-@item (srfi srfi-10)
-Read hash extension @code{#,()} (@pxref{SRFI-10}).
-
-@item (srfi srfi-11)
-Multiple-value handling with @code{let-values} and @code{let*-values}
-(@pxref{SRFI-11}).
-
-@item (srfi srfi-13)
-String library (@pxref{SRFI-13}).
-
-@item (srfi srfi-14)
-Character-set library (@pxref{SRFI-14}).
-
-@item (srfi srfi-16)
-@code{case-lambda} procedures of variable arity (@pxref{SRFI-16}).
-
-@item (srfi srfi-17)
-Getter-with-setter support (@pxref{SRFI-17}).
-
-@item (srfi srfi-19)
-Time/Date library (@pxref{SRFI-19}).
-
-@item (srfi srfi-26)
-Convenient syntax for partial application (@pxref{SRFI-26})
-
-@item (srfi srfi-31)
-@code{rec} convenient recursive expressions (@pxref{SRFI-31})
-
-@item (ice-9 slib)
-This module contains hooks for using Aubrey Jaffer's portable Scheme
-library SLIB from Guile (@pxref{SLIB}).
-@end table
+For more information on where and how to install Scheme modules,
+@xref{Installing Site Packages}.
@node R6RS Version References
@lisp
(library (mylib (1 2))
- (import (otherlib (3)))
- (export mybinding))
+ (export mybinding)
+ (import (otherlib (3))))
@end lisp
is equivalent to the module definition:
@end deffn
+@node Variables
+@subsection Variables
+@tpindex Variables
+
+Each module has its own hash table, sometimes known as an @dfn{obarray},
+that maps the names defined in that module to their corresponding
+variable objects.
+
+A variable is a box-like object that can hold any Scheme value. It is
+said to be @dfn{undefined} if its box holds a special Scheme value that
+denotes undefined-ness (which is different from all other Scheme values,
+including for example @code{#f}); otherwise the variable is
+@dfn{defined}.
+
+On its own, a variable object is anonymous. A variable is said to be
+@dfn{bound} when it is associated with a name in some way, usually a
+symbol in a module obarray. When this happens, the name is said to be
+bound to the variable, in that module.
+
+(That's the theory, anyway. In practice, defined-ness and bound-ness
+sometimes get confused, because Lisp and Scheme implementations have
+often conflated --- or deliberately drawn no distinction between --- a
+name that is unbound and a name that is bound to a variable whose value
+is undefined. We will try to be clear about the difference and explain
+any confusion where it is unavoidable.)
+
+Variables do not have a read syntax. Most commonly they are created and
+bound implicitly by @code{define} expressions: a top-level @code{define}
+expression of the form
+
+@lisp
+(define @var{name} @var{value})
+@end lisp
+
+@noindent
+creates a variable with initial value @var{value} and binds it to the
+name @var{name} in the current module. But they can also be created
+dynamically by calling one of the constructor procedures
+@code{make-variable} and @code{make-undefined-variable}.
+
+@deffn {Scheme Procedure} make-undefined-variable
+@deffnx {C Function} scm_make_undefined_variable ()
+Return a variable that is initially unbound.
+@end deffn
+
+@deffn {Scheme Procedure} make-variable init
+@deffnx {C Function} scm_make_variable (init)
+Return a variable initialized to value @var{init}.
+@end deffn
+
+@deffn {Scheme Procedure} variable-bound? var
+@deffnx {C Function} scm_variable_bound_p (var)
+Return @code{#t} if @var{var} is bound to a value, or @code{#f}
+otherwise. Throws an error if @var{var} is not a variable object.
+@end deffn
+
+@deffn {Scheme Procedure} variable-ref var
+@deffnx {C Function} scm_variable_ref (var)
+Dereference @var{var} and return its value.
+@var{var} must be a variable object; see @code{make-variable}
+and @code{make-undefined-variable}.
+@end deffn
+
+@deffn {Scheme Procedure} variable-set! var val
+@deffnx {C Function} scm_variable_set_x (var, val)
+Set the value of the variable @var{var} to @var{val}.
+@var{var} must be a variable object, @var{val} can be any
+value. Return an unspecified value.
+@end deffn
+
+@deffn {Scheme Procedure} variable-unset! var
+@deffnx {C Function} scm_variable_unset_x (var)
+Unset the value of the variable @var{var}, leaving @var{var} unbound.
+@end deffn
+
+@deffn {Scheme Procedure} variable? obj
+@deffnx {C Function} scm_variable_p (obj)
+Return @code{#t} if @var{obj} is a variable object, else return
+@code{#f}.
+@end deffn
+
+
+@node Module System Reflection
+@subsection Module System Reflection
+
+The previous sections have described a declarative view of the module
+system. You can also work with it programmatically by accessing and
+modifying various parts of the Scheme objects that Guile uses to
+implement the module system.
+
+At any time, there is a @dfn{current module}. This module is the one
+where a top-level @code{define} and similar syntax will add new
+bindings. You can find other module objects with @code{resolve-module},
+for example.
+
+These module objects can be used as the second argument to @code{eval}.
+
+@deffn {Scheme Procedure} current-module
+@deffnx {C Function} scm_current_module ()
+Return the current module object.
+@end deffn
+
+@deffn {Scheme Procedure} set-current-module module
+@deffnx {C Function} scm_set_current_module (module)
+Set the current module to @var{module} and return
+the previous current module.
+@end deffn
+
+@deffn {Scheme Procedure} save-module-excursion thunk
+Call @var{thunk} within a @code{dynamic-wind} such that the module that
+is current at invocation time is restored when @var{thunk}'s dynamic
+extent is left (@pxref{Dynamic Wind}).
+
+More precisely, if @var{thunk} escapes non-locally, the current module
+(at the time of escape) is saved, and the original current module (at
+the time @var{thunk}'s dynamic extent was last entered) is restored. If
+@var{thunk}'s dynamic extent is re-entered, then the current module is
+saved, and the previously saved inner module is set current again.
+@end deffn
+
+@deffn {Scheme Procedure} resolve-module name [autoload=#t] [version=#f] @
+ [#:ensure=#t]
+@deffnx {C Function} scm_resolve_module (name)
+Find the module named @var{name} and return it. When it has not already
+been defined and @var{autoload} is true, try to auto-load it. When it
+can't be found that way either, create an empty module if @var{ensure}
+is true, otherwise return @code{#f}. If @var{version} is true, ensure
+that the resulting module is compatible with the given version reference
+(@pxref{R6RS Version References}). The name is a list of symbols.
+@end deffn
+
+@deffn {Scheme Procedure} resolve-interface name [#:select=#f] @
+ [#:hide='()] [#:prefix=#f] @
+ [#:renamer=#f] [#:version=#f]
+Find the module named @var{name} as with @code{resolve-module} and
+return its interface. The interface of a module is also a module
+object, but it contains only the exported bindings.
+@end deffn
+
+@deffn {Scheme Procedure} module-uses module
+Return a list of the interfaces used by @var{module}.
+@end deffn
+
+@deffn {Scheme Procedure} module-use! module interface
+Add @var{interface} to the front of the use-list of @var{module}. Both
+arguments should be module objects, and @var{interface} should very
+likely be a module returned by @code{resolve-interface}.
+@end deffn
+
+@deffn {Scheme Procedure} reload-module module
+Revisit the source file that corresponds to @var{module}. Raises an
+error if no source file is associated with the given module.
+@end deffn
+
+As mentioned in the previous section, modules contain a mapping between
+identifiers (as symbols) and storage locations (as variables). Guile
+defines a number of procedures to allow access to this mapping. If you
+are programming in C, @ref{Accessing Modules from C}.
+
+@deffn {Scheme Procedure} module-variable module name
+Return the variable bound to @var{name} (a symbol) in @var{module}, or
+@code{#f} if @var{name} is unbound.
+@end deffn
+
+@deffn {Scheme Procedure} module-add! module name var
+Define a new binding between @var{name} (a symbol) and @var{var} (a
+variable) in @var{module}.
+@end deffn
+
+@deffn {Scheme Procedure} module-ref module name
+Look up the value bound to @var{name} in @var{module}. Like
+@code{module-variable}, but also does a @code{variable-ref} on the
+resulting variable, raising an error if @var{name} is unbound.
+@end deffn
+
+@deffn {Scheme Procedure} module-define! module name value
+Locally bind @var{name} to @var{value} in @var{module}. If @var{name}
+was already locally bound in @var{module}, i.e., defined locally and not
+by an imported module, the value stored in the existing variable will be
+updated. Otherwise, a new variable will be added to the module, via
+@code{module-add!}.
+@end deffn
+
+@deffn {Scheme Procedure} module-set! module name value
+Update the binding of @var{name} in @var{module} to @var{value}, raising
+an error if @var{name} is not already bound in @var{module}.
+@end deffn
+
+There are many other reflective procedures available in the default
+environment. If you find yourself using one of them, please contact the
+Guile developers so that we can commit to stability for that interface.
+
+
@node Accessing Modules from C
@subsection Accessing Modules from C
The following procedures are available.
-@deftypefn {C Function} SCM scm_current_module ()
-Return the module that is the @emph{current module}.
-@end deftypefn
-
-@deftypefn {C Function} SCM scm_set_current_module (SCM @var{module})
-Set the current module to @var{module} and return the previous current
-module.
-@end deftypefn
-
@deftypefn {C Function} SCM scm_c_call_with_current_module (SCM @var{module}, SCM (*@var{func})(void *), void *@var{data})
Call @var{func} and make @var{module} the current module during the
call. The argument @var{data} is passed to @var{func}. The return
variable, always.
@example
-SCM my_eval_string (SCM str)
-@{
- static SCM eval_string_var = SCM_BOOL_F;
+static SCM eval_string_var;
- if (scm_is_false (eval_string_var))
- eval_string_var =
- scm_c_public_lookup ("ice-9 eval-string", "eval-string");
+/* NOTE: It is important that the call to 'my_init'
+ happens-before all calls to 'my_eval_string'. */
+void my_init (void)
+@{
+ eval_string_var = scm_c_public_lookup ("ice-9 eval-string",
+ "eval-string");
+@}
+SCM my_eval_string (SCM str)
+@{
return scm_call_1 (scm_variable_ref (eval_string_var), str);
@}
@end example
Like @code{scm_public_lookup} or @code{scm_private_lookup}, but
additionally dereferences the variable. If the variable object is
unbound, signals an error. Returns the value bound to @var{name} in
-@var{module}.
+@var{module_name}.
@end deftypefn
In addition, there are a number of other lookup-related procedures. We
module is used instead of the current one.
@end deftypefn
+In some rare cases, you may need to access the variable that
+@code{scm_module_define} would have accessed, without changing the
+binding of the existing variable, if one is present. In that case, use
+@code{scm_module_ensure_local_variable}:
+
+@deftypefn {C Function} SCM scm_module_ensure_local_variable (SCM @var{module}, SCM @var{sym})
+Like @code{scm_module_define}, but if the @var{sym} is already locally
+bound in that module, the variable's existing binding is not reset.
+Returns a variable.
+@end deftypefn
+
@deftypefn {C Function} SCM scm_module_reverse_lookup (SCM @var{module}, SCM @var{variable})
-Find the symbol that is bound to @var{variable} in @var{module}. When no such binding is found, return @var{#f}.
+Find the symbol that is bound to @var{variable} in @var{module}. When no such binding is found, return @code{#f}.
@end deftypefn
@deftypefn {C Function} SCM scm_c_define_module ({const char *}@var{name}, void (*@var{init})(void *), void *@var{data})
for @code{scm_c_define_module}.
@end deftypefn
-@deftypefn {C Function} SCM scm_resolve_module (SCM @var{name})
-Like @code{scm_c_resolve_module}, but the name is given as a real list
-of symbols.
-@end deftypefn
-
@deftypefn {C Function} SCM scm_c_use_module ({const char *}@var{name})
Add the module named @var{name} to the uses list of the current
module, as with @code{(use-modules @var{name})}. The name is
interpreted as for @code{scm_c_define_module}.
@end deftypefn
-@deftypefn {C Function} SCM scm_c_export ({const char *}@var{name}, ...)
+@deftypefn {C Function} void scm_c_export ({const char *}@var{name}, ...)
Add the bindings designated by @var{name}, ... to the public interface
of the current module. The list of names is terminated by
@code{NULL}.
@end deftypefn
-@node Variables
-@subsection Variables
-@tpindex Variables
-
-Each module has its own hash table, sometimes known as an @dfn{obarray},
-that maps the names defined in that module to their corresponding
-variable objects.
-
-A variable is a box-like object that can hold any Scheme value. It is
-said to be @dfn{undefined} if its box holds a special Scheme value that
-denotes undefined-ness (which is different from all other Scheme values,
-including for example @code{#f}); otherwise the variable is
-@dfn{defined}.
-
-On its own, a variable object is anonymous. A variable is said to be
-@dfn{bound} when it is associated with a name in some way, usually a
-symbol in a module obarray. When this happens, the relationship is
-mutual: the variable is bound to the name (in that module), and the name
-(in that module) is bound to the variable.
-
-(That's the theory, anyway. In practice, defined-ness and bound-ness
-sometimes get confused, because Lisp and Scheme implementations have
-often conflated --- or deliberately drawn no distinction between --- a
-name that is unbound and a name that is bound to a variable whose value
-is undefined. We will try to be clear about the difference and explain
-any confusion where it is unavoidable.)
-
-Variables do not have a read syntax. Most commonly they are created and
-bound implicitly by @code{define} expressions: a top-level @code{define}
-expression of the form
-
-@lisp
-(define @var{name} @var{value})
-@end lisp
-
-@noindent
-creates a variable with initial value @var{value} and binds it to the
-name @var{name} in the current module. But they can also be created
-dynamically by calling one of the constructor procedures
-@code{make-variable} and @code{make-undefined-variable}.
-
-@deffn {Scheme Procedure} make-undefined-variable
-@deffnx {C Function} scm_make_undefined_variable ()
-Return a variable that is initially unbound.
-@end deffn
-
-@deffn {Scheme Procedure} make-variable init
-@deffnx {C Function} scm_make_variable (init)
-Return a variable initialized to value @var{init}.
-@end deffn
-
-@deffn {Scheme Procedure} variable-bound? var
-@deffnx {C Function} scm_variable_bound_p (var)
-Return @code{#t} iff @var{var} is bound to a value.
-Throws an error if @var{var} is not a variable object.
-@end deffn
-
-@deffn {Scheme Procedure} variable-ref var
-@deffnx {C Function} scm_variable_ref (var)
-Dereference @var{var} and return its value.
-@var{var} must be a variable object; see @code{make-variable}
-and @code{make-undefined-variable}.
-@end deffn
-
-@deffn {Scheme Procedure} variable-set! var val
-@deffnx {C Function} scm_variable_set_x (var, val)
-Set the value of the variable @var{var} to @var{val}.
-@var{var} must be a variable object, @var{val} can be any
-value. Return an unspecified value.
-@end deffn
-
-@deffn {Scheme Procedure} variable-unset! var
-@deffnx {C Function} scm_variable_unset_x (var)
-Unset the value of the variable @var{var}, leaving @var{var} unbound.
-@end deffn
-
-@deffn {Scheme Procedure} variable? obj
-@deffnx {C Function} scm_variable_p (obj)
-Return @code{#t} iff @var{obj} is a variable object, else
-return @code{#f}.
-@end deffn
-
-
@node provide and require
@subsection provide and require
HCoop / bpt / guile.git / blobdiff