@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
-@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2006, 2007, 2008, 2009
-@c Free Software Foundation, Inc.
+@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2006, 2007, 2008,
+@c 2009, 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.
-@page
@node SRFI Support
@section SRFI Support Modules
@cindex SRFI
over the available SRFIs and some usage hints. For complete
documentation, design rationales and further examples, we advise you to
get the relevant SRFI documents from the SRFI home page
-@url{http://srfi.schemers.org}.
+@url{http://srfi.schemers.org/}.
@menu
* About SRFI Usage:: What to know about Guile's SRFI support.
* SRFI-17:: Generalized set!
* SRFI-18:: Multithreading support
* SRFI-19:: Time/Date library.
+* SRFI-23:: Error reporting
* SRFI-26:: Specializing parameters
+* SRFI-27:: Sources of Random Bits
* SRFI-30:: Nested multi-line block comments
* SRFI-31:: A special form `rec' for recursive evaluation
* SRFI-34:: Exception handling.
* SRFI-35:: Conditions.
* SRFI-37:: args-fold program argument processor
+* SRFI-38:: External Representation for Data With Shared Structure
* SRFI-39:: Parameter objects
+* SRFI-41:: Streams.
+* SRFI-42:: Eager comprehensions
+* SRFI-43:: Vector Library.
+* SRFI-45:: Primitives for expressing iterative lazy algorithms
+* SRFI-46:: Basic syntax-rules Extensions.
* SRFI-55:: Requiring Features.
* SRFI-60:: Integers as bits.
* SRFI-61:: A more general `cond' clause
+* SRFI-62:: S-expression comments.
+* SRFI-64:: A Scheme API for test suites.
+* SRFI-67:: Compare procedures
* SRFI-69:: Basic hash tables.
+* SRFI-87:: => in case clauses.
* SRFI-88:: Keyword objects.
* SRFI-98:: Accessing environment variables.
+* SRFI-105:: Curly-infix expressions.
+* SRFI-111:: Boxes.
@end menu
it is safe to use @code{use-modules} to load SRFI support modules. The
second reason is that some features defined in SRFIs had been
implemented in Guile before the developers started to add SRFI
-implementations as modules (for example SRFI-6 (@pxref{SRFI-6})). In
+implementations as modules (for example SRFI-13 (@pxref{SRFI-13})). In
the future, it is possible that SRFIs in the core library might be
factored out into separate modules, requiring explicit module loading
when they are needed. So you should be prepared to have to use
-@code{use-modules} someday in the future to access SRFI-6 bindings. If
+@code{use-modules} someday in the future to access SRFI-13 bindings. If
you want, you can do that already. We have included the module
-@code{(srfi srfi-6)} in the distribution, which currently does nothing,
+@code{(srfi srfi-13)} in the distribution, which currently does nothing,
but ensures that you can write future-safe code.
Generally, support for a specific SRFI is made available by using
r5rs
srfi-0
srfi-4
-srfi-6
srfi-13
srfi-14
+srfi-16
+srfi-23
+srfi-30
+srfi-39
+srfi-46
+srfi-55
+srfi-61
+srfi-62
+srfi-87
+srfi-105
@end example
Other SRFI feature symbols are defined once their code has been loaded
@end deffn
@deffn {Scheme Procedure} take-right lst i
-Return the a list containing the @var{i} last elements of @var{lst}.
+Return a list containing the @var{i} last elements of @var{lst}.
The return shares a common tail with @var{lst}.
@end deffn
@deffn {Scheme Procedure} drop-right lst i
@deffnx {Scheme Procedure} drop-right! lst i
-Return the a list containing all but the @var{i} last elements of
+Return a list containing all but the @var{i} last elements of
@var{lst}.
@code{drop-right} always returns a new list, even when @var{i} is
containing the second elements of each lists, and so on.
@end deffn
-@deffn {Scheme Procedure} count pred lst1 @dots{} lstN
+@deffn {Scheme Procedure} count pred lst1 lst2 @dots{}
Return a count of the number of times @var{pred} returns true when
called on elements from the given lists.
@var{pred} is called with @var{N} parameters @code{(@var{pred}
-@var{elem1} @dots{} @var{elemN})}, each element being from the
-corresponding @var{lst1} @dots{} @var{lstN}. The first call is with
-the first element of each list, the second with the second element
-from each, and so on.
+@var{elem1} @dots{} @var{elemN} )}, each element being from the
+corresponding list. The first call is with the first element of each
+list, the second with the second element from each, and so on.
Counting stops when the end of the shortest list is reached. At least
one list must be non-circular.
@c FIXME::martin: Review me!
-@deffn {Scheme Procedure} fold proc init lst1 @dots{} lstN
-@deffnx {Scheme Procedure} fold-right proc init lst1 @dots{} lstN
-Apply @var{proc} to the elements of @var{lst1} @dots{} @var{lstN} to
+@deffn {Scheme Procedure} fold proc init lst1 lst2 @dots{}
+@deffnx {Scheme Procedure} fold-right proc init lst1 lst2 @dots{}
+Apply @var{proc} to the elements of @var{lst1} @var{lst2} @dots{} to
build a result, and return that result.
-Each @var{proc} call is @code{(@var{proc} @var{elem1} @dots{}
-@var{elemN} @var{previous})}, where @var{elem1} is from @var{lst1},
-through @var{elemN} from @var{lstN}. @var{previous} is the return
+Each @var{proc} call is @code{(@var{proc} @var{elem1} @var{elem2}
+@dots{} @var{previous})}, where @var{elem1} is from @var{lst1},
+@var{elem2} is from @var{lst2}, and so on. @var{previous} is the return
from the previous call to @var{proc}, or the given @var{init} for the
first call. If any list is empty, just @var{init} is returned.
@result{} "xyz"
@end example
-If @var{lst1} through @var{lstN} have different lengths, @code{fold}
+If @var{lst1} @var{lst2} @dots{} have different lengths, @code{fold}
stops when the end of the shortest is reached; @code{fold-right}
-commences at the last element of the shortest. Ie.@: elements past
-the length of the shortest are ignored in the other @var{lst}s. At
-least one @var{lst} must be non-circular.
+commences at the last element of the shortest. Ie.@: elements past the
+length of the shortest are ignored in the other @var{lst}s. At least
+one @var{lst} must be non-circular.
@code{fold} should be preferred over @code{fold-right} if the order of
processing doesn't matter, or can be arranged either way, since
@code{for-each} would have to be written out each time.
@end deffn
-@deffn {Scheme Procedure} pair-fold proc init lst1 @dots{} lstN
-@deffnx {Scheme Procedure} pair-fold-right proc init lst1 @dots{} lstN
+@deffn {Scheme Procedure} pair-fold proc init lst1 lst2 @dots{}
+@deffnx {Scheme Procedure} pair-fold-right proc init lst1 lst2 @dots{}
The same as @code{fold} and @code{fold-right}, but apply @var{proc} to
the pairs of the lists instead of the list elements.
@end deffn
Maps each seed value to the corresponding list element.
@item g
-Maps each seed value to next seed valu.
+Maps each seed value to next seed value.
@item seed
The state value for the unfold.
Maps each seed value to the corresponding list element.
@item g
-Maps each seed value to next seed valu.
+Maps each seed value to next seed value.
@item seed
The state value for the unfold.
-@item tail-gen
-Creates the tail of the list; defaults to @code{(lambda (x) '())}.
+@item tail
+The tail of the list; defaults to @code{'()}.
@end table
@end deffn
to make a new define under a different name.
@end deffn
-@deffn {Scheme Procedure} any pred lst1 lst2 @dots{} lstN
-Test whether any set of elements from @var{lst1} @dots{} lstN
-satisfies @var{pred}. If so the return value is the return from the
-successful @var{pred} call, or if not the return is @code{#f}.
+@deffn {Scheme Procedure} any pred lst1 lst2 @dots{}
+Test whether any set of elements from @var{lst1} @var{lst2} @dots{}
+satisfies @var{pred}. If so, the return value is the return value from
+the successful @var{pred} call, or if not, the return value is
+@code{#f}.
-Each @var{pred} call is @code{(@var{pred} @var{elem1} @dots{}
-@var{elemN})} taking an element from each @var{lst}. The calls are
-made successively for the first, second, etc elements of the lists,
-stopping when @var{pred} returns non-@code{#f}, or when the end of the
-shortest list is reached.
+If there are n list arguments, then @var{pred} must be a predicate
+taking n arguments. Each @var{pred} call is @code{(@var{pred}
+@var{elem1} @var{elem2} @dots{} )} taking an element from each
+@var{lst}. The calls are made successively for the first, second, etc.
+elements of the lists, stopping when @var{pred} returns non-@code{#f},
+or when the end of the shortest list is reached.
-The @var{pred} call on the last set of elements (ie.@: when the end of
+The @var{pred} call on the last set of elements (i.e., when the end of
the shortest list has been reached), if that point is reached, is a
tail call.
@end deffn
-@deffn {Scheme Procedure} every pred lst1 lst2 @dots{} lstN
-Test whether every set of elements from @var{lst1} @dots{} lstN
-satisfies @var{pred}. If so the return value is the return from the
-final @var{pred} call, or if not the return is @code{#f}.
+@deffn {Scheme Procedure} every pred lst1 lst2 @dots{}
+Test whether every set of elements from @var{lst1} @var{lst2} @dots{}
+satisfies @var{pred}. If so, the return value is the return from the
+final @var{pred} call, or if not, the return value is @code{#f}.
-Each @var{pred} call is @code{(@var{pred} @var{elem1} @dots{}
-@var{elemN})} taking an element from each @var{lst}. The calls are
-made successively for the first, second, etc elements of the lists,
-stopping if @var{pred} returns @code{#f}, or when the end of any of
-the lists is reached.
+If there are n list arguments, then @var{pred} must be a predicate
+taking n arguments. Each @var{pred} call is @code{(@var{pred}
+@var{elem1} @var{elem2 @dots{}})} taking an element from each
+@var{lst}. The calls are made successively for the first, second, etc.
+elements of the lists, stopping if @var{pred} returns @code{#f}, or when
+the end of any of the lists is reached.
-The @var{pred} call on the last set of elements (ie.@: when the end of
+The @var{pred} call on the last set of elements (i.e., when the end of
the shortest list has been reached) is a tail call.
-If one of @var{lst1} @dots{} @var{lstN} is empty then no calls to
-@var{pred} are made, and the return is @code{#t}.
+If one of @var{lst1} @var{lst2} @dots{}is empty then no calls to
+@var{pred} are made, and the return value is @code{#t}.
@end deffn
-@deffn {Scheme Procedure} list-index pred lst1 @dots{} lstN
+@deffn {Scheme Procedure} list-index pred lst1 lst2 @dots{}
Return the index of the first set of elements, one from each of
-@var{lst1}@dots{}@var{lstN}, which satisfies @var{pred}.
+@var{lst1} @var{lst2} @dots{}, which satisfies @var{pred}.
-@var{pred} is called as @code{(@var{pred} elem1 @dots{} elemN)}.
+@var{pred} is called as @code{(@var{elem1} @var{elem2 @dots{}})}.
Searching stops when the end of the shortest @var{lst} is reached.
The return index starts from 0 for the first set of elements. If no
-set of elements pass then the return is @code{#f}.
+set of elements pass, then the return value is @code{#f}.
@example
(list-index odd? '(2 4 6 9)) @result{} 3
taking an optional @var{=} comparison procedure.
The default comparison is @code{equal?}. If an @var{=} parameter is
-given it's called @code{(@var{=} @var{key} @var{alistcar})}, ie. the
+given it's called @code{(@var{=} @var{key} @var{alistcar})}, i.e.@: the
given target @var{key} is the first argument, and a @code{car} from
@var{alist} is second.
Equality is determined by the @var{=} predicate, or @code{equal?} if
not given. The order in which elements are tested is unspecified, but
-each equality call is made @code{(= key alistkey)}, ie. the given
+each equality call is made @code{(= key alistkey)}, i.e.@: the given
@var{key} parameter is first and the key from @var{alist} second.
This means for instance all associations with a key greater than 5 can
be removed with @code{(alist-delete 5 alist <)}.
@code{eq?} then they must also be equal under the predicate. This
simply means a given object must be equal to itself.
-@deffn {Scheme Procedure} lset<= = list1 list2 @dots{}
+@deffn {Scheme Procedure} lset<= = list @dots{}
Return @code{#t} if each list is a subset of the one following it.
-Ie.@: @var{list1} a subset of @var{list2}, @var{list2} a subset of
-@var{list3}, etc, for as many lists as given. If only one list or no
-lists are given then the return is @code{#t}.
+I.e., @var{list1} is a subset of @var{list2}, @var{list2} is a subset of
+@var{list3}, etc., for as many lists as given. If only one list or no
+lists are given, the return value is @code{#t}.
A list @var{x} is a subset of @var{y} if each element of @var{x} is
equal to some element in @var{y}. Elements are compared using the
@end example
@end deffn
-@deffn {Scheme Procedure} lset= = list1 list2 @dots{}
+@deffn {Scheme Procedure} lset= = list @dots{}
Return @code{#t} if all argument lists are set-equal. @var{list1} is
-compared to @var{list2}, @var{list2} to @var{list3}, etc, for as many
-lists as given. If only one list or no lists are given then the
-return is @code{#t}.
+compared to @var{list2}, @var{list2} to @var{list3}, etc., for as many
+lists as given. If only one list or no lists are given, the return
+value is @code{#t}.
Two lists @var{x} and @var{y} are set-equal if each element of @var{x}
is equal to some element of @var{y} and conversely each element of
@end example
@end deffn
-@deffn {Scheme Procedure} lset-adjoin = list elem1 @dots{}
-Add to @var{list} any of the given @var{elem}s not already in the
-list. @var{elem}s are @code{cons}ed onto the start of @var{list} (so
-the return shares a common tail with @var{list}), but the order
-they're added is unspecified.
+@deffn {Scheme Procedure} lset-adjoin = list elem @dots{}
+Add to @var{list} any of the given @var{elem}s not already in the list.
+@var{elem}s are @code{cons}ed onto the start of @var{list} (so the
+return value shares a common tail with @var{list}), but the order that
+the @var{elem}s are added is unspecified.
The given @var{=} procedure is used for comparing elements, called as
-@code{(@var{=} listelem elem)}, ie.@: the second argument is one of
+@code{(@var{=} listelem elem)}, i.e., the second argument is one of
the given @var{elem} parameters.
@example
@end example
@end deffn
-@deffn {Scheme Procedure} lset-union = list1 list2 @dots{}
-@deffnx {Scheme Procedure} lset-union! = list1 list2 @dots{}
+@deffn {Scheme Procedure} lset-union = list @dots{}
+@deffnx {Scheme Procedure} lset-union! = list @dots{}
Return the union of the argument list sets. The result is built by
taking the union of @var{list1} and @var{list2}, then the union of
-that with @var{list3}, etc, for as many lists as given. For one list
+that with @var{list3}, etc., for as many lists as given. For one list
argument that list itself is the result, for no list arguments the
result is the empty list.
@var{list1} to form its results.
@end deffn
-@deffn {Scheme Procedure} lset-xor = list1 list2 @dots{}
-@deffnx {Scheme Procedure} lset-xor! = list1 list2 @dots{}
+@deffn {Scheme Procedure} lset-xor = list @dots{}
+@deffnx {Scheme Procedure} lset-xor! = list @dots{}
Return an XOR of the argument lists. For two lists this means those
elements which are in exactly one of the lists. For more than two
lists it means those elements which appear in an odd number of the
(use-modules (srfi srfi-2))
@end lisp
+or alternatively
+
+@lisp
+(use-modules (ice-9 and-let-star))
+@end lisp
+
@deffn {library syntax} and-let* (clause @dots{}) body @dots{}
A combination of @code{and} and @code{let*}.
@subsection SRFI-4 - Homogeneous numeric vector datatypes
@cindex SRFI-4
-The SRFI-4 procedures and data types are always available, @xref{Uniform
-Numeric Vectors}.
+SRFI-4 provides an interface to uniform numeric vectors: vectors whose elements
+are all of a single numeric type. Guile offers uniform numeric vectors for
+signed and unsigned 8-bit, 16-bit, 32-bit, and 64-bit integers, two sizes of
+floating point values, and, as an extension to SRFI-4, complex floating-point
+numbers of these two sizes.
-@node SRFI-6
-@subsection SRFI-6 - Basic String Ports
-@cindex SRFI-6
+The standard SRFI-4 procedures and data types may be included via loading the
+appropriate module:
-SRFI-6 defines the procedures @code{open-input-string},
-@code{open-output-string} and @code{get-output-string}. These
-procedures are included in the Guile core, so using this module does not
-make any difference at the moment. But it is possible that support for
-SRFI-6 will be factored out of the core library in the future, so using
-this module does not hurt, after all.
+@example
+(use-modules (srfi srfi-4))
+@end example
-@node SRFI-8
-@subsection SRFI-8 - receive
-@cindex SRFI-8
+This module is currently a part of the default Guile environment, but it is a
+good practice to explicitly import the module. In the future, using SRFI-4
+procedures without importing the SRFI-4 module will cause a deprecation message
+to be printed. (Of course, one may call the C functions at any time. Would that
+C had modules!)
-@code{receive} is a syntax for making the handling of multiple-value
-procedures easier. It is documented in @xref{Multiple Values}.
+@menu
+* SRFI-4 Overview:: The warp and weft of uniform numeric vectors.
+* SRFI-4 API:: Uniform vectors, from Scheme and from C.
+* SRFI-4 Generic Operations:: The general, operating on the specific.
+* SRFI-4 and Bytevectors:: SRFI-4 vectors are backed by bytevectors.
+* SRFI-4 Extensions:: Guile-specific extensions to the standard.
+@end menu
+@node SRFI-4 Overview
+@subsubsection SRFI-4 - Overview
-@node SRFI-9
-@subsection SRFI-9 - define-record-type
-@cindex SRFI-9
-@cindex record
+Uniform numeric vectors can be useful since they consume less memory
+than the non-uniform, general vectors. Also, since the types they can
+store correspond directly to C types, it is easier to work with them
+efficiently on a low level. Consider image processing as an example,
+where you want to apply a filter to some image. While you could store
+the pixels of an image in a general vector and write a general
+convolution function, things are much more efficient with uniform
+vectors: the convolution function knows that all pixels are unsigned
+8-bit values (say), and can use a very tight inner loop.
-This SRFI is a syntax for defining new record types and creating
-predicate, constructor, and field getter and setter functions. In
-Guile this is simply an alternate interface to the core record
-functionality (@pxref{Records}). It can be used with,
+This is implemented in Scheme by having the compiler notice calls to the SRFI-4
+accessors, and inline them to appropriate compiled code. From C you have access
+to the raw array; functions for efficiently working with uniform numeric vectors
+from C are listed at the end of this section.
-@example
-(use-modules (srfi srfi-9))
-@end example
+Uniform numeric vectors are the special case of one dimensional uniform
+numeric arrays.
-@deffn {library syntax} define-record-type type @* (constructor fieldname @dots{}) @* predicate @* (fieldname accessor [modifier]) @dots{}
-@sp 1
-Create a new record type, and make various @code{define}s for using
-it. This syntax can only occur at the top-level, not nested within
-some other form.
+There are 12 standard kinds of uniform numeric vectors, and they all have their
+own complement of constructors, accessors, and so on. Procedures that operate on
+a specific kind of uniform numeric vector have a ``tag'' in their name,
+indicating the element type.
+
+@table @nicode
+@item u8
+unsigned 8-bit integers
+
+@item s8
+signed 8-bit integers
+
+@item u16
+unsigned 16-bit integers
+
+@item s16
+signed 16-bit integers
+
+@item u32
+unsigned 32-bit integers
+
+@item s32
+signed 32-bit integers
-@var{type} is bound to the record type, which is as per the return
-from the core @code{make-record-type}. @var{type} also provides the
-name for the record, as per @code{record-type-name}.
+@item u64
+unsigned 64-bit integers
-@var{constructor} is bound to a function to be called as
-@code{(@var{constructor} fieldval @dots{})} to create a new record of
-this type. The arguments are initial values for the fields, one
-argument for each field, in the order they appear in the
-@code{define-record-type} form.
+@item s64
+signed 64-bit integers
-The @var{fieldname}s provide the names for the record fields, as per
-the core @code{record-type-fields} etc, and are referred to in the
-subsequent accessor/modifier forms.
+@item f32
+the C type @code{float}
-@var{predictate} is bound to a function to be called as
-@code{(@var{predicate} obj)}. It returns @code{#t} or @code{#f}
-according to whether @var{obj} is a record of this type.
+@item f64
+the C type @code{double}
-Each @var{accessor} is bound to a function to be called
-@code{(@var{accessor} record)} to retrieve the respective field from a
-@var{record}. Similarly each @var{modifier} is bound to a function to
-be called @code{(@var{modifier} record val)} to set the respective
-field in a @var{record}.
+@end table
+
+In addition, Guile supports uniform arrays of complex numbers, with the
+nonstandard tags:
+
+@table @nicode
+
+@item c32
+complex numbers in rectangular form with the real and imaginary part
+being a @code{float}
+
+@item c64
+complex numbers in rectangular form with the real and imaginary part
+being a @code{double}
+
+@end table
+
+The external representation (ie.@: read syntax) for these vectors is
+similar to normal Scheme vectors, but with an additional tag from the
+tables above indicating the vector's type. For example,
+
+@lisp
+#u16(1 2 3)
+#f64(3.1415 2.71)
+@end lisp
+
+Note that the read syntax for floating-point here conflicts with
+@code{#f} for false. In Standard Scheme one can write @code{(1 #f3)}
+for a three element list @code{(1 #f 3)}, but for Guile @code{(1 #f3)}
+is invalid. @code{(1 #f 3)} is almost certainly what one should write
+anyway to make the intention clear, so this is rarely a problem.
+
+
+@node SRFI-4 API
+@subsubsection SRFI-4 - API
+
+Note that the @nicode{c32} and @nicode{c64} functions are only available from
+@nicode{(srfi srfi-4 gnu)}.
+
+@deffn {Scheme Procedure} u8vector? obj
+@deffnx {Scheme Procedure} s8vector? obj
+@deffnx {Scheme Procedure} u16vector? obj
+@deffnx {Scheme Procedure} s16vector? obj
+@deffnx {Scheme Procedure} u32vector? obj
+@deffnx {Scheme Procedure} s32vector? obj
+@deffnx {Scheme Procedure} u64vector? obj
+@deffnx {Scheme Procedure} s64vector? obj
+@deffnx {Scheme Procedure} f32vector? obj
+@deffnx {Scheme Procedure} f64vector? obj
+@deffnx {Scheme Procedure} c32vector? obj
+@deffnx {Scheme Procedure} c64vector? obj
+@deffnx {C Function} scm_u8vector_p (obj)
+@deffnx {C Function} scm_s8vector_p (obj)
+@deffnx {C Function} scm_u16vector_p (obj)
+@deffnx {C Function} scm_s16vector_p (obj)
+@deffnx {C Function} scm_u32vector_p (obj)
+@deffnx {C Function} scm_s32vector_p (obj)
+@deffnx {C Function} scm_u64vector_p (obj)
+@deffnx {C Function} scm_s64vector_p (obj)
+@deffnx {C Function} scm_f32vector_p (obj)
+@deffnx {C Function} scm_f64vector_p (obj)
+@deffnx {C Function} scm_c32vector_p (obj)
+@deffnx {C Function} scm_c64vector_p (obj)
+Return @code{#t} if @var{obj} is a homogeneous numeric vector of the
+indicated type.
@end deffn
-@noindent
-An example will illustrate typical usage,
+@deffn {Scheme Procedure} make-u8vector n [value]
+@deffnx {Scheme Procedure} make-s8vector n [value]
+@deffnx {Scheme Procedure} make-u16vector n [value]
+@deffnx {Scheme Procedure} make-s16vector n [value]
+@deffnx {Scheme Procedure} make-u32vector n [value]
+@deffnx {Scheme Procedure} make-s32vector n [value]
+@deffnx {Scheme Procedure} make-u64vector n [value]
+@deffnx {Scheme Procedure} make-s64vector n [value]
+@deffnx {Scheme Procedure} make-f32vector n [value]
+@deffnx {Scheme Procedure} make-f64vector n [value]
+@deffnx {Scheme Procedure} make-c32vector n [value]
+@deffnx {Scheme Procedure} make-c64vector n [value]
+@deffnx {C Function} scm_make_u8vector (n, value)
+@deffnx {C Function} scm_make_s8vector (n, value)
+@deffnx {C Function} scm_make_u16vector (n, value)
+@deffnx {C Function} scm_make_s16vector (n, value)
+@deffnx {C Function} scm_make_u32vector (n, value)
+@deffnx {C Function} scm_make_s32vector (n, value)
+@deffnx {C Function} scm_make_u64vector (n, value)
+@deffnx {C Function} scm_make_s64vector (n, value)
+@deffnx {C Function} scm_make_f32vector (n, value)
+@deffnx {C Function} scm_make_f64vector (n, value)
+@deffnx {C Function} scm_make_c32vector (n, value)
+@deffnx {C Function} scm_make_c64vector (n, value)
+Return a newly allocated homogeneous numeric vector holding @var{n}
+elements of the indicated type. If @var{value} is given, the vector
+is initialized with that value, otherwise the contents are
+unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} u8vector value @dots{}
+@deffnx {Scheme Procedure} s8vector value @dots{}
+@deffnx {Scheme Procedure} u16vector value @dots{}
+@deffnx {Scheme Procedure} s16vector value @dots{}
+@deffnx {Scheme Procedure} u32vector value @dots{}
+@deffnx {Scheme Procedure} s32vector value @dots{}
+@deffnx {Scheme Procedure} u64vector value @dots{}
+@deffnx {Scheme Procedure} s64vector value @dots{}
+@deffnx {Scheme Procedure} f32vector value @dots{}
+@deffnx {Scheme Procedure} f64vector value @dots{}
+@deffnx {Scheme Procedure} c32vector value @dots{}
+@deffnx {Scheme Procedure} c64vector value @dots{}
+@deffnx {C Function} scm_u8vector (values)
+@deffnx {C Function} scm_s8vector (values)
+@deffnx {C Function} scm_u16vector (values)
+@deffnx {C Function} scm_s16vector (values)
+@deffnx {C Function} scm_u32vector (values)
+@deffnx {C Function} scm_s32vector (values)
+@deffnx {C Function} scm_u64vector (values)
+@deffnx {C Function} scm_s64vector (values)
+@deffnx {C Function} scm_f32vector (values)
+@deffnx {C Function} scm_f64vector (values)
+@deffnx {C Function} scm_c32vector (values)
+@deffnx {C Function} scm_c64vector (values)
+Return a newly allocated homogeneous numeric vector of the indicated
+type, holding the given parameter @var{value}s. The vector length is
+the number of parameters given.
+@end deffn
+
+@deffn {Scheme Procedure} u8vector-length vec
+@deffnx {Scheme Procedure} s8vector-length vec
+@deffnx {Scheme Procedure} u16vector-length vec
+@deffnx {Scheme Procedure} s16vector-length vec
+@deffnx {Scheme Procedure} u32vector-length vec
+@deffnx {Scheme Procedure} s32vector-length vec
+@deffnx {Scheme Procedure} u64vector-length vec
+@deffnx {Scheme Procedure} s64vector-length vec
+@deffnx {Scheme Procedure} f32vector-length vec
+@deffnx {Scheme Procedure} f64vector-length vec
+@deffnx {Scheme Procedure} c32vector-length vec
+@deffnx {Scheme Procedure} c64vector-length vec
+@deffnx {C Function} scm_u8vector_length (vec)
+@deffnx {C Function} scm_s8vector_length (vec)
+@deffnx {C Function} scm_u16vector_length (vec)
+@deffnx {C Function} scm_s16vector_length (vec)
+@deffnx {C Function} scm_u32vector_length (vec)
+@deffnx {C Function} scm_s32vector_length (vec)
+@deffnx {C Function} scm_u64vector_length (vec)
+@deffnx {C Function} scm_s64vector_length (vec)
+@deffnx {C Function} scm_f32vector_length (vec)
+@deffnx {C Function} scm_f64vector_length (vec)
+@deffnx {C Function} scm_c32vector_length (vec)
+@deffnx {C Function} scm_c64vector_length (vec)
+Return the number of elements in @var{vec}.
+@end deffn
+
+@deffn {Scheme Procedure} u8vector-ref vec i
+@deffnx {Scheme Procedure} s8vector-ref vec i
+@deffnx {Scheme Procedure} u16vector-ref vec i
+@deffnx {Scheme Procedure} s16vector-ref vec i
+@deffnx {Scheme Procedure} u32vector-ref vec i
+@deffnx {Scheme Procedure} s32vector-ref vec i
+@deffnx {Scheme Procedure} u64vector-ref vec i
+@deffnx {Scheme Procedure} s64vector-ref vec i
+@deffnx {Scheme Procedure} f32vector-ref vec i
+@deffnx {Scheme Procedure} f64vector-ref vec i
+@deffnx {Scheme Procedure} c32vector-ref vec i
+@deffnx {Scheme Procedure} c64vector-ref vec i
+@deffnx {C Function} scm_u8vector_ref (vec, i)
+@deffnx {C Function} scm_s8vector_ref (vec, i)
+@deffnx {C Function} scm_u16vector_ref (vec, i)
+@deffnx {C Function} scm_s16vector_ref (vec, i)
+@deffnx {C Function} scm_u32vector_ref (vec, i)
+@deffnx {C Function} scm_s32vector_ref (vec, i)
+@deffnx {C Function} scm_u64vector_ref (vec, i)
+@deffnx {C Function} scm_s64vector_ref (vec, i)
+@deffnx {C Function} scm_f32vector_ref (vec, i)
+@deffnx {C Function} scm_f64vector_ref (vec, i)
+@deffnx {C Function} scm_c32vector_ref (vec, i)
+@deffnx {C Function} scm_c64vector_ref (vec, i)
+Return the element at index @var{i} in @var{vec}. The first element
+in @var{vec} is index 0.
+@end deffn
+
+@deffn {Scheme Procedure} u8vector-set! vec i value
+@deffnx {Scheme Procedure} s8vector-set! vec i value
+@deffnx {Scheme Procedure} u16vector-set! vec i value
+@deffnx {Scheme Procedure} s16vector-set! vec i value
+@deffnx {Scheme Procedure} u32vector-set! vec i value
+@deffnx {Scheme Procedure} s32vector-set! vec i value
+@deffnx {Scheme Procedure} u64vector-set! vec i value
+@deffnx {Scheme Procedure} s64vector-set! vec i value
+@deffnx {Scheme Procedure} f32vector-set! vec i value
+@deffnx {Scheme Procedure} f64vector-set! vec i value
+@deffnx {Scheme Procedure} c32vector-set! vec i value
+@deffnx {Scheme Procedure} c64vector-set! vec i value
+@deffnx {C Function} scm_u8vector_set_x (vec, i, value)
+@deffnx {C Function} scm_s8vector_set_x (vec, i, value)
+@deffnx {C Function} scm_u16vector_set_x (vec, i, value)
+@deffnx {C Function} scm_s16vector_set_x (vec, i, value)
+@deffnx {C Function} scm_u32vector_set_x (vec, i, value)
+@deffnx {C Function} scm_s32vector_set_x (vec, i, value)
+@deffnx {C Function} scm_u64vector_set_x (vec, i, value)
+@deffnx {C Function} scm_s64vector_set_x (vec, i, value)
+@deffnx {C Function} scm_f32vector_set_x (vec, i, value)
+@deffnx {C Function} scm_f64vector_set_x (vec, i, value)
+@deffnx {C Function} scm_c32vector_set_x (vec, i, value)
+@deffnx {C Function} scm_c64vector_set_x (vec, i, value)
+Set the element at index @var{i} in @var{vec} to @var{value}. The
+first element in @var{vec} is index 0. The return value is
+unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} u8vector->list vec
+@deffnx {Scheme Procedure} s8vector->list vec
+@deffnx {Scheme Procedure} u16vector->list vec
+@deffnx {Scheme Procedure} s16vector->list vec
+@deffnx {Scheme Procedure} u32vector->list vec
+@deffnx {Scheme Procedure} s32vector->list vec
+@deffnx {Scheme Procedure} u64vector->list vec
+@deffnx {Scheme Procedure} s64vector->list vec
+@deffnx {Scheme Procedure} f32vector->list vec
+@deffnx {Scheme Procedure} f64vector->list vec
+@deffnx {Scheme Procedure} c32vector->list vec
+@deffnx {Scheme Procedure} c64vector->list vec
+@deffnx {C Function} scm_u8vector_to_list (vec)
+@deffnx {C Function} scm_s8vector_to_list (vec)
+@deffnx {C Function} scm_u16vector_to_list (vec)
+@deffnx {C Function} scm_s16vector_to_list (vec)
+@deffnx {C Function} scm_u32vector_to_list (vec)
+@deffnx {C Function} scm_s32vector_to_list (vec)
+@deffnx {C Function} scm_u64vector_to_list (vec)
+@deffnx {C Function} scm_s64vector_to_list (vec)
+@deffnx {C Function} scm_f32vector_to_list (vec)
+@deffnx {C Function} scm_f64vector_to_list (vec)
+@deffnx {C Function} scm_c32vector_to_list (vec)
+@deffnx {C Function} scm_c64vector_to_list (vec)
+Return a newly allocated list holding all elements of @var{vec}.
+@end deffn
+
+@deffn {Scheme Procedure} list->u8vector lst
+@deffnx {Scheme Procedure} list->s8vector lst
+@deffnx {Scheme Procedure} list->u16vector lst
+@deffnx {Scheme Procedure} list->s16vector lst
+@deffnx {Scheme Procedure} list->u32vector lst
+@deffnx {Scheme Procedure} list->s32vector lst
+@deffnx {Scheme Procedure} list->u64vector lst
+@deffnx {Scheme Procedure} list->s64vector lst
+@deffnx {Scheme Procedure} list->f32vector lst
+@deffnx {Scheme Procedure} list->f64vector lst
+@deffnx {Scheme Procedure} list->c32vector lst
+@deffnx {Scheme Procedure} list->c64vector lst
+@deffnx {C Function} scm_list_to_u8vector (lst)
+@deffnx {C Function} scm_list_to_s8vector (lst)
+@deffnx {C Function} scm_list_to_u16vector (lst)
+@deffnx {C Function} scm_list_to_s16vector (lst)
+@deffnx {C Function} scm_list_to_u32vector (lst)
+@deffnx {C Function} scm_list_to_s32vector (lst)
+@deffnx {C Function} scm_list_to_u64vector (lst)
+@deffnx {C Function} scm_list_to_s64vector (lst)
+@deffnx {C Function} scm_list_to_f32vector (lst)
+@deffnx {C Function} scm_list_to_f64vector (lst)
+@deffnx {C Function} scm_list_to_c32vector (lst)
+@deffnx {C Function} scm_list_to_c64vector (lst)
+Return a newly allocated homogeneous numeric vector of the indicated type,
+initialized with the elements of the list @var{lst}.
+@end deffn
+
+@deftypefn {C Function} SCM scm_take_u8vector (const scm_t_uint8 *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_s8vector (const scm_t_int8 *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_u16vector (const scm_t_uint16 *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_s16vector (const scm_t_int16 *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_u32vector (const scm_t_uint32 *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_s32vector (const scm_t_int32 *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_u64vector (const scm_t_uint64 *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_s64vector (const scm_t_int64 *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_f32vector (const float *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_f64vector (const double *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_c32vector (const float *data, size_t len)
+@deftypefnx {C Function} SCM scm_take_c64vector (const double *data, size_t len)
+Return a new uniform numeric vector of the indicated type and length
+that uses the memory pointed to by @var{data} to store its elements.
+This memory will eventually be freed with @code{free}. The argument
+@var{len} specifies the number of elements in @var{data}, not its size
+in bytes.
+
+The @code{c32} and @code{c64} variants take a pointer to a C array of
+@code{float}s or @code{double}s. The real parts of the complex numbers
+are at even indices in that array, the corresponding imaginary parts are
+at the following odd index.
+@end deftypefn
+
+@deftypefn {C Function} {const scm_t_uint8 *} scm_u8vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const scm_t_int8 *} scm_s8vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const scm_t_uint16 *} scm_u16vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const scm_t_int16 *} scm_s16vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const scm_t_uint32 *} scm_u32vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const scm_t_int32 *} scm_s32vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const scm_t_uint64 *} scm_u64vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const scm_t_int64 *} scm_s64vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const float *} scm_f32vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const double *} scm_f64vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const float *} scm_c32vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {const double *} scm_c64vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+Like @code{scm_vector_elements} (@pxref{Vector Accessing from C}), but
+returns a pointer to the elements of a uniform numeric vector of the
+indicated kind.
+@end deftypefn
+
+@deftypefn {C Function} {scm_t_uint8 *} scm_u8vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {scm_t_int8 *} scm_s8vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {scm_t_uint16 *} scm_u16vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {scm_t_int16 *} scm_s16vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {scm_t_uint32 *} scm_u32vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {scm_t_int32 *} scm_s32vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {scm_t_uint64 *} scm_u64vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {scm_t_int64 *} scm_s64vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {float *} scm_f32vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {double *} scm_f64vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {float *} scm_c32vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+@deftypefnx {C Function} {double *} scm_c64vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+Like @code{scm_vector_writable_elements} (@pxref{Vector Accessing from
+C}), but returns a pointer to the elements of a uniform numeric vector
+of the indicated kind.
+@end deftypefn
+
+@node SRFI-4 Generic Operations
+@subsubsection SRFI-4 - Generic operations
+
+Guile also provides procedures that operate on all types of uniform numeric
+vectors. In what is probably a bug, these procedures are currently available in
+the default environment as well; however prudent hackers will make sure to
+import @code{(srfi srfi-4 gnu)} before using these.
+
+@deftypefn {C Function} int scm_is_uniform_vector (SCM uvec)
+Return non-zero when @var{uvec} is a uniform numeric vector, zero
+otherwise.
+@end deftypefn
+
+@deftypefn {C Function} size_t scm_c_uniform_vector_length (SCM uvec)
+Return the number of elements of @var{uvec} as a @code{size_t}.
+@end deftypefn
+
+@deffn {Scheme Procedure} uniform-vector? obj
+@deffnx {C Function} scm_uniform_vector_p (obj)
+Return @code{#t} if @var{obj} is a homogeneous numeric vector of the
+indicated type.
+@end deffn
+
+@deffn {Scheme Procedure} uniform-vector-length vec
+@deffnx {C Function} scm_uniform_vector_length (vec)
+Return the number of elements in @var{vec}.
+@end deffn
+
+@deffn {Scheme Procedure} uniform-vector-ref vec i
+@deffnx {C Function} scm_uniform_vector_ref (vec, i)
+Return the element at index @var{i} in @var{vec}. The first element
+in @var{vec} is index 0.
+@end deffn
+
+@deffn {Scheme Procedure} uniform-vector-set! vec i value
+@deffnx {C Function} scm_uniform_vector_set_x (vec, i, value)
+Set the element at index @var{i} in @var{vec} to @var{value}. The
+first element in @var{vec} is index 0. The return value is
+unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} uniform-vector->list vec
+@deffnx {C Function} scm_uniform_vector_to_list (vec)
+Return a newly allocated list holding all elements of @var{vec}.
+@end deffn
+
+@deftypefn {C Function} {const void *} scm_uniform_vector_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+Like @code{scm_vector_elements} (@pxref{Vector Accessing from C}), but
+returns a pointer to the elements of a uniform numeric vector.
+@end deftypefn
+
+@deftypefn {C Function} {void *} scm_uniform_vector_writable_elements (SCM vec, scm_t_array_handle *handle, size_t *lenp, ssize_t *incp)
+Like @code{scm_vector_writable_elements} (@pxref{Vector Accessing from
+C}), but returns a pointer to the elements of a uniform numeric vector.
+@end deftypefn
+
+Unless you really need to the limited generality of these functions, it
+is best to use the type-specific functions, or the array accessors.
+
+@node SRFI-4 and Bytevectors
+@subsubsection SRFI-4 - Relation to bytevectors
+
+Guile implements SRFI-4 vectors using bytevectors (@pxref{Bytevectors}). Often
+when you have a numeric vector, you end up wanting to write its bytes somewhere,
+or have access to the underlying bytes, or read in bytes from somewhere else.
+Bytevectors are very good at this sort of thing. But the SRFI-4 APIs are nicer
+to use when doing number-crunching, because they are addressed by element and
+not by byte.
+
+So as a compromise, Guile allows all bytevector functions to operate on numeric
+vectors. They address the underlying bytes in the native endianness, as one
+would expect.
+
+Following the same reasoning, that it's just bytes underneath, Guile also allows
+uniform vectors of a given type to be accessed as if they were of any type. One
+can fill a @nicode{u32vector}, and access its elements with
+@nicode{u8vector-ref}. One can use @nicode{f64vector-ref} on bytevectors. It's
+all the same to Guile.
+
+In this way, uniform numeric vectors may be written to and read from
+input/output ports using the procedures that operate on bytevectors.
+
+@xref{Bytevectors}, for more information.
+
+
+@node SRFI-4 Extensions
+@subsubsection SRFI-4 - Guile extensions
+
+Guile defines some useful extensions to SRFI-4, which are not available in the
+default Guile environment. They may be imported by loading the extensions
+module:
@example
-(define-record-type employee-type
- (make-employee name age salary)
- employee?
- (name get-employee-name)
- (age get-employee-age set-employee-age)
- (salary get-employee-salary set-employee-salary))
+(use-modules (srfi srfi-4 gnu))
@end example
-This creates a new employee data type, with name, age and salary
-fields. Accessor functions are created for each field, but no
-modifier function for the name (the intention in this example being
-that it's established only when an employee object is created). These
-can all then be used as for example,
+@deffn {Scheme Procedure} any->u8vector obj
+@deffnx {Scheme Procedure} any->s8vector obj
+@deffnx {Scheme Procedure} any->u16vector obj
+@deffnx {Scheme Procedure} any->s16vector obj
+@deffnx {Scheme Procedure} any->u32vector obj
+@deffnx {Scheme Procedure} any->s32vector obj
+@deffnx {Scheme Procedure} any->u64vector obj
+@deffnx {Scheme Procedure} any->s64vector obj
+@deffnx {Scheme Procedure} any->f32vector obj
+@deffnx {Scheme Procedure} any->f64vector obj
+@deffnx {Scheme Procedure} any->c32vector obj
+@deffnx {Scheme Procedure} any->c64vector obj
+@deffnx {C Function} scm_any_to_u8vector (obj)
+@deffnx {C Function} scm_any_to_s8vector (obj)
+@deffnx {C Function} scm_any_to_u16vector (obj)
+@deffnx {C Function} scm_any_to_s16vector (obj)
+@deffnx {C Function} scm_any_to_u32vector (obj)
+@deffnx {C Function} scm_any_to_s32vector (obj)
+@deffnx {C Function} scm_any_to_u64vector (obj)
+@deffnx {C Function} scm_any_to_s64vector (obj)
+@deffnx {C Function} scm_any_to_f32vector (obj)
+@deffnx {C Function} scm_any_to_f64vector (obj)
+@deffnx {C Function} scm_any_to_c32vector (obj)
+@deffnx {C Function} scm_any_to_c64vector (obj)
+Return a (maybe newly allocated) uniform numeric vector of the indicated
+type, initialized with the elements of @var{obj}, which must be a list,
+a vector, or a uniform vector. When @var{obj} is already a suitable
+uniform numeric vector, it is returned unchanged.
+@end deffn
+
-@example
-employee-type @result{} #<record-type employee-type>
+@node SRFI-6
+@subsection SRFI-6 - Basic String Ports
+@cindex SRFI-6
+
+SRFI-6 defines the procedures @code{open-input-string},
+@code{open-output-string} and @code{get-output-string}.
+
+Note that although versions of these procedures are included in the
+Guile core, the core versions are not fully conformant with SRFI-6:
+attempts to read or write characters that are not supported by the
+current @code{%default-port-encoding} will fail.
-(define fred (make-employee "Fred" 45 20000.00))
+We therefore recommend that you import this module, which supports all
+characters:
-(employee? fred) @result{} #t
-(get-employee-age fred) @result{} 45
-(set-employee-salary fred 25000.00) ;; pay rise
+@example
+(use-modules (srfi srfi-6))
@end example
-The functions created by @code{define-record-type} are ordinary
-top-level @code{define}s. They can be redefined or @code{set!} as
-desired, exported from a module, etc.
+@node SRFI-8
+@subsection SRFI-8 - receive
+@cindex SRFI-8
+
+@code{receive} is a syntax for making the handling of multiple-value
+procedures easier. It is documented in @xref{Multiple Values}.
+
+
+@node SRFI-9
+@subsection SRFI-9 - define-record-type
+
+This SRFI is a syntax for defining new record types and creating
+predicate, constructor, and field getter and setter functions. It is
+documented in the ``Compound Data Types'' section of the manual
+(@pxref{SRFI-9 Records}).
@node SRFI-10
@deffn {Scheme Procedure} define-reader-ctor tag proc
Register @var{proc} as the constructor for a hash-comma read syntax
-starting with symbol @var{tag}, ie. @nicode{#,(@var{tag} arg@dots{})}.
+starting with symbol @var{tag}, i.e.@: @nicode{#,(@var{tag} arg@dots{})}.
@var{proc} is called with the given arguments @code{(@var{proc}
arg@dots{})} and the object it returns is the result of the read.
@end deffn
Wait for @var{thread} to terminate and return its exit value. When a
time value @var{timeout} is given, it specifies a point in time where
the waiting should be aborted. When the waiting is aborted,
-@var{timeoutval} is returned if it is specified; otherwise, a
+@var{timeout-val} is returned if it is specified; otherwise, a
@code{join-timeout-exception} exception is raised
(@pxref{SRFI-18 Exceptions}). Exceptions may also be raised if the
thread was terminated by a call to @code{thread-terminate!}
@end defun
@defun condition-variable-name condition-variable
-Returns the name assigned to @var{thread} at the time of its creation,
-or @code{#f} if it was not given a name.
+Returns the name assigned to @var{condition-variable} at the time of its
+creation, or @code{#f} if it was not given a name.
@end defun
@defun condition-variable-specific condition-variable
@item @nicode{~z} @tab time zone, RFC-822 style
@item @nicode{~Z} @tab time zone symbol (not currently implemented)
@item @nicode{~1} @tab ISO-8601 date, @samp{~Y-~m-~d}
-@item @nicode{~2} @tab ISO-8601 time+zone, @samp{~k:~M:~S~z}
-@item @nicode{~3} @tab ISO-8601 time, @samp{~k:~M:~S}
-@item @nicode{~4} @tab ISO-8601 date/time+zone, @samp{~Y-~m-~dT~k:~M:~S~z}
-@item @nicode{~5} @tab ISO-8601 date/time, @samp{~Y-~m-~dT~k:~M:~S}
+@item @nicode{~2} @tab ISO-8601 time+zone, @samp{~H:~M:~S~z}
+@item @nicode{~3} @tab ISO-8601 time, @samp{~H:~M:~S}
+@item @nicode{~4} @tab ISO-8601 date/time+zone, @samp{~Y-~m-~dT~H:~M:~S~z}
+@item @nicode{~5} @tab ISO-8601 date/time, @samp{~Y-~m-~dT~H:~M:~S}
@end multitable
@end defun
@cindex date, from string
@c FIXME: Can we say what happens when an incomplete date is
-@c converted? Ie. fields left as 0, or what? The spec seems to be
+@c converted? I.e. fields left as 0, or what? The spec seems to be
@c silent on this.
@defun string->date input template
locale.
@end defun
+@node SRFI-23
+@subsection SRFI-23 - Error Reporting
+@cindex SRFI-23
+
+The SRFI-23 @code{error} procedure is always available.
@node SRFI-26
@subsection SRFI-26 - specializing parameters
(use-modules (srfi srfi-26))
@end example
-@deffn {library syntax} cut slot @dots{}
-@deffnx {library syntax} cute slot @dots{}
-Return a new procedure which will make a call (@var{slot} @dots{}) but
-with selected parameters specialized to given expressions.
+@deffn {library syntax} cut slot1 slot2 @dots{}
+@deffnx {library syntax} cute slot1 slot2 @dots{}
+Return a new procedure which will make a call (@var{slot1} @var{slot2}
+@dots{}) but with selected parameters specialized to given expressions.
An example will illustrate the idea. The following is a
specialization of @code{write}, sending output to
@end example
@end deffn
+@node SRFI-27
+@subsection SRFI-27 - Sources of Random Bits
+@cindex SRFI-27
+
+This subsection is based on the
+@uref{http://srfi.schemers.org/srfi-27/srfi-27.html, specification of
+SRFI-27} written by Sebastian Egner.
+
+@c The copyright notice and license text of the SRFI-27 specification is
+@c reproduced below:
+
+@c Copyright (C) Sebastian Egner (2002). All Rights Reserved.
+
+@c Permission is hereby granted, free of charge, to any person obtaining a
+@c copy of this software and associated documentation files (the
+@c "Software"), to deal in the Software without restriction, including
+@c without limitation the rights to use, copy, modify, merge, publish,
+@c distribute, sublicense, and/or sell copies of the Software, and to
+@c permit persons to whom the Software is furnished to do so, subject to
+@c the following conditions:
+
+@c The above copyright notice and this permission notice shall be included
+@c in all copies or substantial portions of the Software.
+
+@c THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+@c OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+@c MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+@c NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+@c LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+@c OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+@c WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+This SRFI provides access to a (pseudo) random number generator; for
+Guile's built-in random number facilities, which SRFI-27 is implemented
+upon, @xref{Random}. With SRFI-27, random numbers are obtained from a
+@emph{random source}, which encapsulates a random number generation
+algorithm and its state.
+
+@menu
+* SRFI-27 Default Random Source:: Obtaining random numbers
+* SRFI-27 Random Sources:: Creating and manipulating random sources
+* SRFI-27 Random Number Generators:: Obtaining random number generators
+@end menu
+
+@node SRFI-27 Default Random Source
+@subsubsection The Default Random Source
+@cindex SRFI-27
+
+@defun random-integer n
+Return a random number between zero (inclusive) and @var{n} (exclusive),
+using the default random source. The numbers returned have a uniform
+distribution.
+@end defun
+
+@defun random-real
+Return a random number in (0,1), using the default random source. The
+numbers returned have a uniform distribution.
+@end defun
+
+@defun default-random-source
+A random source from which @code{random-integer} and @code{random-real}
+have been derived using @code{random-source-make-integers} and
+@code{random-source-make-reals} (@pxref{SRFI-27 Random Number Generators}
+for those procedures). Note that an assignment to
+@code{default-random-source} does not change @code{random-integer} or
+@code{random-real}; it is also strongly recommended not to assign a new
+value.
+@end defun
+
+@node SRFI-27 Random Sources
+@subsubsection Random Sources
+@cindex SRFI-27
+
+@defun make-random-source
+Create a new random source. The stream of random numbers obtained from
+each random source created by this procedure will be identical, unless
+its state is changed by one of the procedures below.
+@end defun
+
+@defun random-source? object
+Tests whether @var{object} is a random source. Random sources are a
+disjoint type.
+@end defun
+
+@defun random-source-randomize! source
+Attempt to set the state of the random source to a truly random value.
+The current implementation uses a seed based on the current system time.
+@end defun
+
+@defun random-source-pseudo-randomize! source i j
+Changes the state of the random source s into the initial state of the
+(@var{i}, @var{j})-th independent random source, where @var{i} and
+@var{j} are non-negative integers. This procedure provides a mechanism
+to obtain a large number of independent random sources (usually all
+derived from the same backbone generator), indexed by two integers. In
+contrast to @code{random-source-randomize!}, this procedure is entirely
+deterministic.
+@end defun
+
+The state associated with a random state can be obtained an reinstated
+with the following procedures:
+
+@defun random-source-state-ref source
+@defunx random-source-state-set! source state
+Get and set the state of a random source. No assumptions should be made
+about the nature of the state object, besides it having an external
+representation (i.e.@: it can be passed to @code{write} and subsequently
+@code{read} back).
+@end defun
+
+@node SRFI-27 Random Number Generators
+@subsubsection Obtaining random number generator procedures
+@cindex SRFI-27
+
+@defun random-source-make-integers source
+Obtains a procedure to generate random integers using the random source
+@var{source}. The returned procedure takes a single argument @var{n},
+which must be a positive integer, and returns the next uniformly
+distributed random integer from the interval @{0, ..., @var{n}-1@} by
+advancing the state of @var{source}.
+
+If an application obtains and uses several generators for the same
+random source @var{source}, a call to any of these generators advances
+the state of @var{source}. Hence, the generators do not produce the
+same sequence of random integers each but rather share a state. This
+also holds for all other types of generators derived from a fixed random
+sources.
+
+While the SRFI text specifies that ``Implementations that support
+concurrency make sure that the state of a generator is properly
+advanced'', this is currently not the case in Guile's implementation of
+SRFI-27, as it would cause a severe performance penalty. So in
+multi-threaded programs, you either must perform locking on random
+sources shared between threads yourself, or use different random sources
+for multiple threads.
+@end defun
+
+@defun random-source-make-reals source
+@defunx random-source-make-reals source unit
+Obtains a procedure to generate random real numbers @math{0 < x < 1}
+using the random source @var{source}. The procedure rand is called
+without arguments.
+
+The optional parameter @var{unit} determines the type of numbers being
+produced by the returned procedure and the quantization of the output.
+@var{unit} must be a number such that @math{0 < @var{unit} < 1}. The
+numbers created by the returned procedure are of the same numerical type
+as @var{unit} and the potential output values are spaced by at most
+@var{unit}. One can imagine rand to create numbers as @var{x} *
+@var{unit} where @var{x} is a random integer in @{1, ...,
+floor(1/unit)-1@}. Note, however, that this need not be the way the
+values are actually created and that the actual resolution of rand can
+be much higher than unit. In case @var{unit} is absent it defaults to a
+reasonably small value (related to the width of the mantissa of an
+efficient number format).
+@end defun
+
@node SRFI-30
@subsection SRFI-30 - Nested Multi-line Comments
@cindex SRFI-30
Note that all fields of @var{type} and its supertypes must be specified.
@end deffn
-@deffn {Scheme Procedure} make-compound-condition . conditions
-Return a new compound condition composed of @var{conditions}. The
-returned condition has the type of each condition of @var{conditions}
-(per @code{condition-has-type?}).
+@deffn {Scheme Procedure} make-compound-condition condition1 condition2 @dots{}
+Return a new compound condition composed of @var{condition1}
+@var{condition2} @enddots{}. The returned condition has the type of
+each condition of condition1 condition2 @dots{} (per
+@code{condition-has-type?}).
@end deffn
@deffn {Scheme Procedure} condition-has-type? c type
If @var{c} is a compound condition and several underlying condition
types contain a field named @var{field-name}, then the value of the
first such field is returned, using the order in which conditions were
-passed to @var{make-compound-condition}.
+passed to @code{make-compound-condition}.
@end deffn
@deffn {Scheme Procedure} extract-condition c type
If @var{c} is a compound condition, extract the field values from the
subcondition belonging to @var{type} that appeared first in the call to
-@code{make-compound-condition} that created the the condition.
+@code{make-compound-condition} that created the condition.
@end deffn
Convenience macros are also available to create condition types and
@end lisp
@end deffn
-@deffn {library syntax} condition type-field-bindings...
-Return a new condition, or compound condition, initialized according to
-@var{type-field-bindings}. Each @var{type-field-binding} must have the
-form @code{(type field-specs...)}, where @var{type} is the name of a
-variable bound to condition type; each @var{field-spec} must have the
-form @code{(field-name value)} where @var{field-name} is a symbol
-denoting the field being initialized to @var{value}. As for
+@deffn {library syntax} condition type-field-binding1 type-field-binding2 @dots{}
+Return a new condition or compound condition, initialized according to
+@var{type-field-binding1} @var{type-field-binding2} @enddots{}. Each
+@var{type-field-binding} must have the form @code{(type
+field-specs...)}, where @var{type} is the name of a variable bound to a
+condition type; each @var{field-spec} must have the form
+@code{(field-name value)} where @var{field-name} is a symbol denoting
+the field being initialized to @var{value}. As for
@code{make-condition}, all fields must be specified.
The following example returns a simple condition:
Return true if @var{c} is of type @code{&error} or one of its subtypes.
@end deffn
-
@node SRFI-37
@subsection SRFI-37 - args-fold
@cindex SRFI-37
described above for @code{option}.
@end deffn
-@deffn {Scheme Procedure} args-fold args options unrecognized-option-proc operand-proc seeds @dots{}
-Process @var{args}, a list of program arguments such as that returned
-by @code{(cdr (program-arguments))}, in order against @var{options}, a
-list of option objects as described above. All functions called take
-the ``seeds'', or the last multiple-values as multiple arguments,
-starting with @var{seeds}, and must return the new seeds. Return the
+@deffn {Scheme Procedure} args-fold args options unrecognized-option-proc operand-proc seed @dots{}
+Process @var{args}, a list of program arguments such as that returned by
+@code{(cdr (program-arguments))}, in order against @var{options}, a list
+of option objects as described above. All functions called take the
+``seeds'', or the last multiple-values as multiple arguments, starting
+with @var{seed} @dots{}, and must return the new seeds. Return the
final seeds.
Call @code{unrecognized-option-proc}, which is like an option object's
called with the argument in question, as well as the seeds.
@end deffn
-
-@node SRFI-39
-@subsection SRFI-39 - Parameters
-@cindex SRFI-39
-@cindex parameter object
-@tindex Parameter
-
-This SRFI provides parameter objects, which implement dynamically
-bound locations for values. The functions below are available from
+@node SRFI-38
+@subsection SRFI-38 - External Representation for Data With Shared Structure
+@cindex SRFI-38
+
+This subsection is based on
+@uref{http://srfi.schemers.org/srfi-38/srfi-38.html, the specification
+of SRFI-38} written by Ray Dillinger.
+
+@c Copyright (C) Ray Dillinger 2003. All Rights Reserved.
+
+@c Permission is hereby granted, free of charge, to any person obtaining a
+@c copy of this software and associated documentation files (the
+@c "Software"), to deal in the Software without restriction, including
+@c without limitation the rights to use, copy, modify, merge, publish,
+@c distribute, sublicense, and/or sell copies of the Software, and to
+@c permit persons to whom the Software is furnished to do so, subject to
+@c the following conditions:
+
+@c The above copyright notice and this permission notice shall be included
+@c in all copies or substantial portions of the Software.
+
+@c THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+@c OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+@c MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+@c NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+@c LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+@c OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+@c WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+This SRFI creates an alternative external representation for data
+written and read using @code{write-with-shared-structure} and
+@code{read-with-shared-structure}. It is identical to the grammar for
+external representation for data written and read with @code{write} and
+@code{read} given in section 7 of R5RS, except that the single
+production
@example
-(use-modules (srfi srfi-39))
+<datum> --> <simple datum> | <compound datum>
@end example
-A parameter object is a procedure. Called with no arguments it
-returns its value, called with one argument it sets the value.
+is replaced by the following five productions:
@example
-(define my-param (make-parameter 123))
-(my-param) @result{} 123
-(my-param 456)
-(my-param) @result{} 456
+<datum> --> <defining datum> | <nondefining datum> | <defined datum>
+<defining datum> --> #<indexnum>=<nondefining datum>
+<defined datum> --> #<indexnum>#
+<nondefining datum> --> <simple datum> | <compound datum>
+<indexnum> --> <digit 10>+
@end example
-The @code{parameterize} special form establishes new locations for
-parameters, those new locations having effect within the dynamic scope
-of the @code{parameterize} body. Leaving restores the previous
-locations, or re-entering through a saved continuation will again use
-the new locations.
+@deffn {Scheme procedure} write-with-shared-structure obj
+@deffnx {Scheme procedure} write-with-shared-structure obj port
+@deffnx {Scheme procedure} write-with-shared-structure obj port optarg
+
+Writes an external representation of @var{obj} to the given port.
+Strings that appear in the written representation are enclosed in
+doublequotes, and within those strings backslash and doublequote
+characters are escaped by backslashes. Character objects are written
+using the @code{#\} notation.
+
+Objects which denote locations rather than values (cons cells, vectors,
+and non-zero-length strings in R5RS scheme; also Guile's structs,
+bytevectors and ports and hash-tables), if they appear at more than one
+point in the data being written, are preceded by @samp{#@var{N}=} the
+first time they are written and replaced by @samp{#@var{N}#} all
+subsequent times they are written, where @var{N} is a natural number
+used to identify that particular object. If objects which denote
+locations occur only once in the structure, then
+@code{write-with-shared-structure} must produce the same external
+representation for those objects as @code{write}.
+
+@code{write-with-shared-structure} terminates in finite time and
+produces a finite representation when writing finite data.
+
+@code{write-with-shared-structure} returns an unspecified value. The
+@var{port} argument may be omitted, in which case it defaults to the
+value returned by @code{(current-output-port)}. The @var{optarg}
+argument may also be omitted. If present, its effects on the output and
+return value are unspecified but @code{write-with-shared-structure} must
+still write a representation that can be read by
+@code{read-with-shared-structure}. Some implementations may wish to use
+@var{optarg} to specify formatting conventions, numeric radixes, or
+return values. Guile's implementation ignores @var{optarg}.
+
+For example, the code
-@example
-(parameterize ((my-param 789))
- (my-param) @result{} 789
- )
-(my-param) @result{} 456
-@end example
+@lisp
+(begin (define a (cons 'val1 'val2))
+ (set-cdr! a a)
+ (write-with-shared-structure a))
+@end lisp
-Parameters are like dynamically bound variables in other Lisp dialets.
-They allow an application to establish parameter settings (as the name
-suggests) just for the execution of a particular bit of code,
-restoring when done. Examples of such parameters might be
-case-sensitivity for a search, or a prompt for user input.
+should produce the output @code{#1=(val1 . #1#)}. This shows a cons
+cell whose @code{cdr} contains itself.
-Global variables are not as good as parameter objects for this sort of
-thing. Changes to them are visible to all threads, but in Guile
-parameter object locations are per-thread, thereby truely limiting the
-effect of @code{parameterize} to just its dynamic execution.
+@end deffn
-Passing arguments to functions is thread-safe, but that soon becomes
-tedious when there's more than a few or when they need to pass down
-through several layers of calls before reaching the point they should
-affect. And introducing a new setting to existing code is often
-easier with a parameter object than adding arguments.
+@deffn {Scheme procedure} read-with-shared-structure
+@deffnx {Scheme procedure} read-with-shared-structure port
+@code{read-with-shared-structure} converts the external representations
+of Scheme objects produced by @code{write-with-shared-structure} into
+Scheme objects. That is, it is a parser for the nonterminal
+@samp{<datum>} in the augmented external representation grammar defined
+above. @code{read-with-shared-structure} returns the next object
+parsable from the given input port, updating @var{port} to point to the
+first character past the end of the external representation of the
+object.
-@sp 1
-@defun make-parameter init [converter]
-Return a new parameter object, with initial value @var{init}.
+If an end-of-file is encountered in the input before any characters are
+found that can begin an object, then an end-of-file object is returned.
+The port remains open, and further attempts to read it (by
+@code{read-with-shared-structure} or @code{read} will also return an
+end-of-file object. If an end of file is encountered after the
+beginning of an object's external representation, but the external
+representation is incomplete and therefore not parsable, an error is
+signalled.
-A parameter object is a procedure. When called @code{(param)} it
-returns its value, or a call @code{(param val)} sets its value. For
-example,
+The @var{port} argument may be omitted, in which case it defaults to the
+value returned by @code{(current-input-port)}. It is an error to read
+from a closed port.
-@example
-(define my-param (make-parameter 123))
-(my-param) @result{} 123
+@end deffn
-(my-param 456)
-(my-param) @result{} 456
-@end example
+@node SRFI-39
+@subsection SRFI-39 - Parameters
+@cindex SRFI-39
-If a @var{converter} is given, then a call @code{(@var{converter}
-val)} is made for each value set, its return is the value stored.
-Such a call is made for the @var{init} initial value too.
+This SRFI adds support for dynamically-scoped parameters. SRFI 39 is
+implemented in the Guile core; there's no module needed to get SRFI-39
+itself. Parameters are documented in @ref{Parameters}.
-A @var{converter} allows values to be validated, or put into a
-canonical form. For example,
+This module does export one extra function: @code{with-parameters*}.
+This is a Guile-specific addition to the SRFI, similar to the core
+@code{with-fluids*} (@pxref{Fluids and Dynamic States}).
-@example
-(define my-param (make-parameter 123
- (lambda (val)
- (if (not (number? val))
- (error "must be a number"))
- (inexact->exact val))))
-(my-param 0.75)
-(my-param) @result{} 3/4
-@end example
+@defun with-parameters* param-list value-list thunk
+Establish a new dynamic scope, as per @code{parameterize} above,
+taking parameters from @var{param-list} and corresponding values from
+@var{value-list}. A call @code{(@var{thunk})} is made in the new
+scope and the result from that @var{thunk} is the return from
+@code{with-parameters*}.
@end defun
-@deffn {library syntax} parameterize ((param value) @dots{}) body @dots{}
-Establish a new dynamic scope with the given @var{param}s bound to new
-locations and set to the given @var{value}s. @var{body} is evaluated
-in that environment, the result is the return from the last form in
-@var{body}.
+@node SRFI-41
+@subsection SRFI-41 - Streams
+@cindex SRFI-41
-Each @var{param} is an expression which is evaluated to get the
-parameter object. Often this will just be the name of a variable
-holding the object, but it can be anything that evaluates to a
-parameter.
+This subsection is based on the
+@uref{http://srfi.schemers.org/srfi-41/srfi-41.html, specification of
+SRFI-41} by Philip L.@: Bewig.
-The @var{param} expressions and @var{value} expressions are all
-evaluated before establishing the new dynamic bindings, and they're
-evaluated in an unspecified order.
+@c The copyright notice and license text of the SRFI-41 specification is
+@c reproduced below:
-For example,
+@c Copyright (C) Philip L. Bewig (2007). All Rights Reserved.
-@example
-(define prompt (make-parameter "Type something: "))
-(define (get-input)
- (display (prompt))
- ...)
+@c Permission is hereby granted, free of charge, to any person obtaining a
+@c copy of this software and associated documentation files (the
+@c "Software"), to deal in the Software without restriction, including
+@c without limitation the rights to use, copy, modify, merge, publish,
+@c distribute, sublicense, and/or sell copies of the Software, and to
+@c permit persons to whom the Software is furnished to do so, subject to
+@c the following conditions:
+
+@c The above copyright notice and this permission notice shall be included
+@c in all copies or substantial portions of the Software.
+
+@c THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+@c OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+@c MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+@c NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+@c LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+@c OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+@c WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+@noindent
+This SRFI implements streams, sometimes called lazy lists, a sequential
+data structure containing elements computed only on demand. A stream is
+either null or is a pair with a stream in its cdr. Since elements of a
+stream are computed only when accessed, streams can be infinite. Once
+computed, the value of a stream element is cached in case it is needed
+again. SRFI-41 can be made available with:
-(parameterize ((prompt "Type a number: "))
- (get-input)
- ...)
+@example
+(use-modules (srfi srfi-41))
@end example
+
+@menu
+* SRFI-41 Stream Fundamentals::
+* SRFI-41 Stream Primitives::
+* SRFI-41 Stream Library::
+@end menu
+
+@node SRFI-41 Stream Fundamentals
+@subsubsection SRFI-41 Stream Fundamentals
+
+SRFI-41 Streams are based on two mutually-recursive abstract data types:
+An object of the @code{stream} abstract data type is a promise that,
+when forced, is either @code{stream-null} or is an object of type
+@code{stream-pair}. An object of the @code{stream-pair} abstract data
+type contains a @code{stream-car} and a @code{stream-cdr}, which must be
+a @code{stream}. The essential feature of streams is the systematic
+suspensions of the recursive promises between the two data types.
+
+The object stored in the @code{stream-car} of a @code{stream-pair} is a
+promise that is forced the first time the @code{stream-car} is accessed;
+its value is cached in case it is needed again. The object may have any
+type, and different stream elements may have different types. If the
+@code{stream-car} is never accessed, the object stored there is never
+evaluated. Likewise, the @code{stream-cdr} is a promise to return a
+stream, and is only forced on demand.
+
+@node SRFI-41 Stream Primitives
+@subsubsection SRFI-41 Stream Primitives
+
+This library provides eight operators: constructors for
+@code{stream-null} and @code{stream-pair}s, type predicates for streams
+and the two kinds of streams, accessors for both fields of a
+@code{stream-pair}, and a lambda that creates procedures that return
+streams.
+
+@defvr {Scheme Variable} stream-null
+A promise that, when forced, is a single object, distinguishable from
+all other objects, that represents the null stream. @code{stream-null}
+is immutable and unique.
+@end defvr
+
+@deffn {Scheme Syntax} stream-cons object-expr stream-expr
+Creates a newly-allocated stream containing a promise that, when forced,
+is a @code{stream-pair} with @var{object-expr} in its @code{stream-car}
+and @var{stream-expr} in its @code{stream-cdr}. Neither
+@var{object-expr} nor @var{stream-expr} is evaluated when
+@code{stream-cons} is called.
+
+Once created, a @code{stream-pair} is immutable; there is no
+@code{stream-set-car!} or @code{stream-set-cdr!} that modifies an
+existing stream-pair. There is no dotted-pair or improper stream as
+with lists.
@end deffn
-@deffn {Parameter object} current-input-port [new-port]
-@deffnx {Parameter object} current-output-port [new-port]
-@deffnx {Parameter object} current-error-port [new-port]
-This SRFI extends the core @code{current-input-port} and
-@code{current-output-port}, making them parameter objects. The
-Guile-specific @code{current-error-port} is extended too, for
-consistency. (@pxref{Default Ports}.)
+@deffn {Scheme Procedure} stream? object
+Returns true if @var{object} is a stream, otherwise returns false. If
+@var{object} is a stream, its promise will not be forced. If
+@code{(stream? obj)} returns true, then one of @code{(stream-null? obj)}
+or @code{(stream-pair? obj)} will return true and the other will return
+false.
+@end deffn
-This is an upwardly compatible extension, a plain call like
-@code{(current-input-port)} still returns the current input port, and
-@code{set-current-input-port} can still be used. But the port can now
-also be set with @code{(current-input-port my-port)} and bound
-dynamically with @code{parameterize}.
+@deffn {Scheme Procedure} stream-null? object
+Returns true if @var{object} is the distinguished null stream, otherwise
+returns false. If @var{object} is a stream, its promise will be forced.
@end deffn
-@defun with-parameters* param-list value-list thunk
-Establish a new dynamic scope, as per @code{parameterize} above,
-taking parameters from @var{param-list} and corresponding values from
-@var{values-list}. A call @code{(@var{thunk})} is made in the new
-scope and the result from that @var{thunk} is the return from
-@code{with-parameters*}.
+@deffn {Scheme Procedure} stream-pair? object
+Returns true if @var{object} is a @code{stream-pair} constructed by
+@code{stream-cons}, otherwise returns false. If @var{object} is a
+stream, its promise will be forced.
+@end deffn
-This function is a Guile-specific addition to the SRFI, it's similar
-to the core @code{with-fluids*} (@pxref{Fluids and Dynamic States}).
-@end defun
+@deffn {Scheme Procedure} stream-car stream
+Returns the object stored in the @code{stream-car} of @var{stream}. An
+error is signalled if the argument is not a @code{stream-pair}. This
+causes the @var{object-expr} passed to @code{stream-cons} to be
+evaluated if it had not yet been; the value is cached in case it is
+needed again.
+@end deffn
+
+@deffn {Scheme Procedure} stream-cdr stream
+Returns the stream stored in the @code{stream-cdr} of @var{stream}. An
+error is signalled if the argument is not a @code{stream-pair}.
+@end deffn
+@deffn {Scheme Syntax} stream-lambda formals body @dots{}
+Creates a procedure that returns a promise to evaluate the @var{body} of
+the procedure. The last @var{body} expression to be evaluated must
+yield a stream. As with normal @code{lambda}, @var{formals} may be a
+single variable name, in which case all the formal arguments are
+collected into a single list, or a list of variable names, which may be
+null if there are no arguments, proper if there are an exact number of
+arguments, or dotted if a fixed number of arguments is to be followed by
+zero or more arguments collected into a list. @var{Body} must contain
+at least one expression, and may contain internal definitions preceding
+any expressions to be evaluated.
+@end deffn
-@sp 1
-Parameter objects are implemented using fluids (@pxref{Fluids and
-Dynamic States}), so each dynamic state has it's own parameter
-locations. That includes the separate locations when outside any
-@code{parameterize} form. When a parameter is created it gets a
-separate initial location in each dynamic state, all initialized to
-the given @var{init} value.
+@example
+(define strm123
+ (stream-cons 1
+ (stream-cons 2
+ (stream-cons 3
+ stream-null))))
-As alluded to above, because each thread usually has a separate
-dynamic state, each thread has it's own locations behind parameter
-objects, and changes in one thread are not visible to any other. When
-a new dynamic state or thread is created, the values of parameters in
-the originating context are copied, into new locations.
+(stream-car strm123) @result{} 1
+(stream-car (stream-cdr strm123) @result{} 2
-SRFI-39 doesn't specify the interaction between parameter objects and
-threads, so the threading behaviour described here should be regarded
-as Guile-specific.
+(stream-pair?
+ (stream-cdr
+ (stream-cons (/ 1 0) stream-null))) @result{} #f
+(stream? (list 1 2 3)) @result{} #f
-@node SRFI-55
-@subsection SRFI-55 - Requiring Features
-@cindex SRFI-55
+(define iter
+ (stream-lambda (f x)
+ (stream-cons x (iter f (f x)))))
-SRFI-55 provides @code{require-extension} which is a portable
-mechanism to load selected SRFI modules. This is implemented in the
-Guile core, there's no module needed to get SRFI-55 itself.
+(define nats (iter (lambda (x) (+ x 1)) 0))
-@deffn {library syntax} require-extension clause@dots{}
-Require each of the given @var{clause} features, throwing an error if
-any are unavailable.
+(stream-car (stream-cdr nats)) @result{} 1
-A @var{clause} is of the form @code{(@var{identifier} arg...)}. The
-only @var{identifier} currently supported is @code{srfi} and the
-arguments are SRFI numbers. For example to get SRFI-1 and SRFI-6,
+(define stream-add
+ (stream-lambda (s1 s2)
+ (stream-cons
+ (+ (stream-car s1) (stream-car s2))
+ (stream-add (stream-cdr s1)
+ (stream-cdr s2)))))
-@example
-(require-extension (srfi 1 6))
+(define evens (stream-add nats nats))
+
+(stream-car evens) @result{} 0
+(stream-car (stream-cdr evens)) @result{} 2
+(stream-car (stream-cdr (stream-cdr evens))) @result{} 4
@end example
-@code{require-extension} can only be used at the top-level.
+@node SRFI-41 Stream Library
+@subsubsection SRFI-41 Stream Library
-A Guile-specific program can simply @code{use-modules} to load SRFIs
-not already in the core, @code{require-extension} is for programs
-designed to be portable to other Scheme implementations.
+@deffn {Scheme Syntax} define-stream (name args @dots{}) body @dots{}
+Creates a procedure that returns a stream, and may appear anywhere a
+normal @code{define} may appear, including as an internal definition.
+It may contain internal definitions of its own. The defined procedure
+takes arguments in the same way as @code{stream-lambda}.
+@code{define-stream} is syntactic sugar on @code{stream-lambda}; see
+also @code{stream-let}, which is also a sugaring of
+@code{stream-lambda}.
+
+A simple version of @code{stream-map} that takes only a single input
+stream calls itself recursively:
+
+@example
+(define-stream (stream-map proc strm)
+ (if (stream-null? strm)
+ stream-null
+ (stream-cons
+ (proc (stream-car strm))
+ (stream-map proc (stream-cdr strm))))))
+@end example
@end deffn
+@deffn {Scheme Procedure} list->stream list
+Returns a newly-allocated stream containing the elements from
+@var{list}.
+@end deffn
-@node SRFI-60
-@subsection SRFI-60 - Integers as Bits
-@cindex SRFI-60
-@cindex integers as bits
-@cindex bitwise logical
+@deffn {Scheme Procedure} port->stream [port]
+Returns a newly-allocated stream containing in its elements the
+characters on the port. If @var{port} is not given it defaults to the
+current input port. The returned stream has finite length and is
+terminated by @code{stream-null}.
-This SRFI provides various functions for treating integers as bits and
-for bitwise manipulations. These functions can be obtained with,
+It looks like one use of @code{port->stream} would be this:
@example
-(use-modules (srfi srfi-60))
+(define s ;wrong!
+ (with-input-from-file filename
+ (lambda () (port->stream))))
@end example
-Integers are treated as infinite precision twos-complement, the same
-as in the core logical functions (@pxref{Bitwise Operations}). And
-likewise bit indexes start from 0 for the least significant bit. The
-following functions in this SRFI are already in the Guile core,
+But that fails, because @code{with-input-from-file} is eager, and closes
+the input port prematurely, before the first character is read. To read
+a file into a stream, say:
-@quotation
-@code{logand},
-@code{logior},
-@code{logxor},
-@code{lognot},
-@code{logtest},
-@code{logcount},
-@code{integer-length},
-@code{logbit?},
-@code{ash}
-@end quotation
+@example
+(define-stream (file->stream filename)
+ (let ((p (open-input-file filename)))
+ (stream-let loop ((c (read-char p)))
+ (if (eof-object? c)
+ (begin (close-input-port p)
+ stream-null)
+ (stream-cons c
+ (loop (read-char p)))))))
+@end example
+@end deffn
-@sp 1
-@defun bitwise-and n1 ...
-@defunx bitwise-ior n1 ...
-@defunx bitwise-xor n1 ...
-@defunx bitwise-not n
-@defunx any-bits-set? j k
-@defunx bit-set? index n
-@defunx arithmetic-shift n count
-@defunx bit-field n start end
-@defunx bit-count n
-Aliases for @code{logand}, @code{logior}, @code{logxor},
-@code{lognot}, @code{logtest}, @code{logbit?}, @code{ash},
-@code{bit-extract} and @code{logcount} respectively.
+@deffn {Scheme Syntax} stream object-expr @dots{}
+Creates a newly-allocated stream containing in its elements the objects,
+in order. The @var{object-expr}s are evaluated when they are accessed,
+not when the stream is created. If no objects are given, as in
+(stream), the null stream is returned. See also @code{list->stream}.
+
+@example
+(define strm123 (stream 1 2 3))
+
+; (/ 1 0) not evaluated when stream is created
+(define s (stream 1 (/ 1 0) -1))
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream->list [n] stream
+Returns a newly-allocated list containing in its elements the first
+@var{n} items in @var{stream}. If @var{stream} has less than @var{n}
+items, all the items in the stream will be included in the returned
+list. If @var{n} is not given it defaults to infinity, which means that
+unless @var{stream} is finite @code{stream->list} will never return.
+
+@example
+(stream->list 10
+ (stream-map (lambda (x) (* x x))
+ (stream-from 0)))
+ @result{} (0 1 4 9 16 25 36 49 64 81)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-append stream @dots{}
+Returns a newly-allocated stream containing in its elements those
+elements contained in its input @var{stream}s, in order of input. If
+any of the input streams is infinite, no elements of any of the
+succeeding input streams will appear in the output stream. See also
+@code{stream-concat}.
+@end deffn
+
+@deffn {Scheme Procedure} stream-concat stream
+Takes a @var{stream} consisting of one or more streams and returns a
+newly-allocated stream containing all the elements of the input streams.
+If any of the streams in the input @var{stream} is infinite, any
+remaining streams in the input stream will never appear in the output
+stream. See also @code{stream-append}.
+@end deffn
+
+@deffn {Scheme Procedure} stream-constant object @dots{}
+Returns a newly-allocated stream containing in its elements the
+@var{object}s, repeating in succession forever.
+
+@example
+(stream-constant 1) @result{} 1 1 1 @dots{}
+(stream-constant #t #f) @result{} #t #f #t #f #t #f @dots{}
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-drop n stream
+Returns the suffix of the input @var{stream} that starts at the next
+element after the first @var{n} elements. The output stream shares
+structure with the input @var{stream}; thus, promises forced in one
+instance of the stream are also forced in the other instance of the
+stream. If the input @var{stream} has less than @var{n} elements,
+@code{stream-drop} returns the null stream. See also
+@code{stream-take}.
+@end deffn
+
+@deffn {Scheme Procedure} stream-drop-while pred stream
+Returns the suffix of the input @var{stream} that starts at the first
+element @var{x} for which @code{(pred x)} returns false. The output
+stream shares structure with the input @var{stream}. See also
+@code{stream-take-while}.
+@end deffn
+
+@deffn {Scheme Procedure} stream-filter pred stream
+Returns a newly-allocated stream that contains only those elements
+@var{x} of the input @var{stream} which satisfy the predicate
+@code{pred}.
+
+@example
+(stream-filter odd? (stream-from 0))
+ @result{} 1 3 5 7 9 @dots{}
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-fold proc base stream
+Applies a binary procedure @var{proc} to @var{base} and the first
+element of @var{stream} to compute a new @var{base}, then applies the
+procedure to the new @var{base} and the next element of @var{stream} to
+compute a succeeding @var{base}, and so on, accumulating a value that is
+finally returned as the value of @code{stream-fold} when the end of the
+stream is reached. @var{stream} must be finite, or @code{stream-fold}
+will enter an infinite loop. See also @code{stream-scan}, which is
+similar to @code{stream-fold}, but useful for infinite streams. For
+readers familiar with other functional languages, this is a left-fold;
+there is no corresponding right-fold, since right-fold relies on finite
+streams that are fully-evaluated, in which case they may as well be
+converted to a list.
+@end deffn
+
+@deffn {Scheme Procedure} stream-for-each proc stream @dots{}
+Applies @var{proc} element-wise to corresponding elements of the input
+@var{stream}s for side-effects; it returns nothing.
+@code{stream-for-each} stops as soon as any of its input streams is
+exhausted.
+@end deffn
+
+@deffn {Scheme Procedure} stream-from first [step]
+Creates a newly-allocated stream that contains @var{first} as its first
+element and increments each succeeding element by @var{step}. If
+@var{step} is not given it defaults to 1. @var{first} and @var{step}
+may be of any numeric type. @code{stream-from} is frequently useful as
+a generator in @code{stream-of} expressions. See also
+@code{stream-range} for a similar procedure that creates finite streams.
+@end deffn
+
+@deffn {Scheme Procedure} stream-iterate proc base
+Creates a newly-allocated stream containing @var{base} in its first
+element and applies @var{proc} to each element in turn to determine the
+succeeding element. See also @code{stream-unfold} and
+@code{stream-unfolds}.
+@end deffn
+
+@deffn {Scheme Procedure} stream-length stream
+Returns the number of elements in the @var{stream}; it does not evaluate
+its elements. @code{stream-length} may only be used on finite streams;
+it enters an infinite loop with infinite streams.
+@end deffn
+
+@deffn {Scheme Syntax} stream-let tag ((var expr) @dots{}) body @dots{}
+Creates a local scope that binds each variable to the value of its
+corresponding expression. It additionally binds @var{tag} to a
+procedure which takes the bound variables as arguments and @var{body} as
+its defining expressions, binding the @var{tag} with
+@code{stream-lambda}. @var{tag} is in scope within body, and may be
+called recursively. When the expanded expression defined by the
+@code{stream-let} is evaluated, @code{stream-let} evaluates the
+expressions in its @var{body} in an environment containing the
+newly-bound variables, returning the value of the last expression
+evaluated, which must yield a stream.
+
+@code{stream-let} provides syntactic sugar on @code{stream-lambda}, in
+the same manner as normal @code{let} provides syntactic sugar on normal
+@code{lambda}. However, unlike normal @code{let}, the @var{tag} is
+required, not optional, because unnamed @code{stream-let} is
+meaningless.
+
+For example, @code{stream-member} returns the first @code{stream-pair}
+of the input @var{strm} with a @code{stream-car} @var{x} that satisfies
+@code{(eql? obj x)}, or the null stream if @var{x} is not present in
+@var{strm}.
+
+@example
+(define-stream (stream-member eql? obj strm)
+ (stream-let loop ((strm strm))
+ (cond ((stream-null? strm) strm)
+ ((eql? obj (stream-car strm)) strm)
+ (else (loop (stream-cdr strm))))))
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-map proc stream @dots{}
+Applies @var{proc} element-wise to corresponding elements of the input
+@var{stream}s, returning a newly-allocated stream containing elements
+that are the results of those procedure applications. The output stream
+has as many elements as the minimum-length input stream, and may be
+infinite.
+@end deffn
+
+@deffn {Scheme Syntax} stream-match stream clause @dots{}
+Provides pattern-matching for streams. The input @var{stream} is an
+expression that evaluates to a stream. Clauses are of the form
+@code{(pattern [fender] expression)}, consisting of a @var{pattern} that
+matches a stream of a particular shape, an optional @var{fender} that
+must succeed if the pattern is to match, and an @var{expression} that is
+evaluated if the pattern matches. There are four types of patterns:
+
+@itemize @bullet
+@item
+() matches the null stream.
+
+@item
+(@var{pat0} @var{pat1} @dots{}) matches a finite stream with length
+exactly equal to the number of pattern elements.
+
+@item
+(@var{pat0} @var{pat1} @dots{} @code{.} @var{pat-rest}) matches an
+infinite stream, or a finite stream with length at least as great as the
+number of pattern elements before the literal dot.
+
+@item
+@var{pat} matches an entire stream. Should always appear last in the
+list of clauses; it's not an error to appear elsewhere, but subsequent
+clauses could never match.
+@end itemize
+
+Each pattern element may be either:
+
+@itemize @bullet
+@item
+An identifier, which matches any stream element. Additionally, the
+value of the stream element is bound to the variable named by the
+identifier, which is in scope in the @var{fender} and @var{expression}
+of the corresponding @var{clause}. Each identifier in a single pattern
+must be unique.
+
+@item
+A literal underscore (@code{_}), which matches any stream element but
+creates no bindings.
+@end itemize
+
+The @var{pattern}s are tested in order, left-to-right, until a matching
+pattern is found; if @var{fender} is present, it must evaluate to a true
+value for the match to be successful. Pattern variables are bound in
+the corresponding @var{fender} and @var{expression}. Once the matching
+@var{pattern} is found, the corresponding @var{expression} is evaluated
+and returned as the result of the match. An error is signaled if no
+pattern matches the input @var{stream}.
+
+@code{stream-match} is often used to distinguish null streams from
+non-null streams, binding @var{head} and @var{tail}:
+
+@example
+(define (len strm)
+ (stream-match strm
+ (() 0)
+ ((head . tail) (+ 1 (len tail)))))
+@end example
+
+Fenders can test the common case where two stream elements must be
+identical; the @code{else} pattern is an identifier bound to the entire
+stream, not a keyword as in @code{cond}.
+
+@example
+(stream-match strm
+ ((x y . _) (equal? x y) 'ok)
+ (else 'error))
+@end example
+
+A more complex example uses two nested matchers to match two different
+stream arguments; @code{(stream-merge lt? . strms)} stably merges two or
+more streams ordered by the @code{lt?} predicate:
+
+@example
+(define-stream (stream-merge lt? . strms)
+ (define-stream (merge xx yy)
+ (stream-match xx (() yy) ((x . xs)
+ (stream-match yy (() xx) ((y . ys)
+ (if (lt? y x)
+ (stream-cons y (merge xx ys))
+ (stream-cons x (merge xs yy))))))))
+ (stream-let loop ((strms strms))
+ (cond ((null? strms) stream-null)
+ ((null? (cdr strms)) (car strms))
+ (else (merge (car strms)
+ (apply stream-merge lt?
+ (cdr strms)))))))
+@end example
+@end deffn
+
+@deffn {Scheme Syntax} stream-of expr clause @dots{}
+Provides the syntax of stream comprehensions, which generate streams by
+means of looping expressions. The result is a stream of objects of the
+type returned by @var{expr}. There are four types of clauses:
+
+@itemize @bullet
+@item
+(@var{var} @code{in} @var{stream-expr}) loops over the elements of
+@var{stream-expr}, in order from the start of the stream, binding each
+element of the stream in turn to @var{var}. @code{stream-from} and
+@code{stream-range} are frequently useful as generators for
+@var{stream-expr}.
+
+@item
+(@var{var} @code{is} @var{expr}) binds @var{var} to the value obtained
+by evaluating @var{expr}.
+
+@item
+(@var{pred} @var{expr}) includes in the output stream only those
+elements @var{x} which satisfy the predicate @var{pred}.
+@end itemize
+
+The scope of variables bound in the stream comprehension is the clauses
+to the right of the binding clause (but not the binding clause itself)
+plus the result expression.
+
+When two or more generators are present, the loops are processed as if
+they are nested from left to right; that is, the rightmost generator
+varies fastest. A consequence of this is that only the first generator
+may be infinite and all subsequent generators must be finite. If no
+generators are present, the result of a stream comprehension is a stream
+containing the result expression; thus, @samp{(stream-of 1)} produces a
+finite stream containing only the element 1.
+
+@example
+(stream-of (* x x)
+ (x in (stream-range 0 10))
+ (even? x))
+ @result{} 0 4 16 36 64
+
+(stream-of (list a b)
+ (a in (stream-range 1 4))
+ (b in (stream-range 1 3)))
+ @result{} (1 1) (1 2) (2 1) (2 2) (3 1) (3 2)
+
+(stream-of (list i j)
+ (i in (stream-range 1 5))
+ (j in (stream-range (+ i 1) 5)))
+ @result{} (1 2) (1 3) (1 4) (2 3) (2 4) (3 4)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-range first past [step]
+Creates a newly-allocated stream that contains @var{first} as its first
+element and increments each succeeding element by @var{step}. The
+stream is finite and ends before @var{past}, which is not an element of
+the stream. If @var{step} is not given it defaults to 1 if @var{first}
+is less than past and -1 otherwise. @var{first}, @var{past} and
+@var{step} may be of any real numeric type. @code{stream-range} is
+frequently useful as a generator in @code{stream-of} expressions. See
+also @code{stream-from} for a similar procedure that creates infinite
+streams.
+
+@example
+(stream-range 0 10) @result{} 0 1 2 3 4 5 6 7 8 9
+(stream-range 0 10 2) @result{} 0 2 4 6 8
+@end example
+
+Successive elements of the stream are calculated by adding @var{step} to
+@var{first}, so if any of @var{first}, @var{past} or @var{step} are
+inexact, the length of the output stream may differ from
+@code{(ceiling (- (/ (- past first) step) 1)}.
+@end deffn
+
+@deffn {Scheme Procedure} stream-ref stream n
+Returns the @var{n}th element of stream, counting from zero. An error
+is signaled if @var{n} is greater than or equal to the length of stream.
+
+@example
+(define (fact n)
+ (stream-ref
+ (stream-scan * 1 (stream-from 1))
+ n))
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-reverse stream
+Returns a newly-allocated stream containing the elements of the input
+@var{stream} but in reverse order. @code{stream-reverse} may only be
+used with finite streams; it enters an infinite loop with infinite
+streams. @code{stream-reverse} does not force evaluation of the
+elements of the stream.
+@end deffn
+
+@deffn {Scheme Procedure} stream-scan proc base stream
+Accumulates the partial folds of an input @var{stream} into a
+newly-allocated output stream. The output stream is the @var{base}
+followed by @code{(stream-fold proc base (stream-take i stream))} for
+each of the first @var{i} elements of @var{stream}.
+
+@example
+(stream-scan + 0 (stream-from 1))
+ @result{} (stream 0 1 3 6 10 15 @dots{})
+
+(stream-scan * 1 (stream-from 1))
+ @result{} (stream 1 1 2 6 24 120 @dots{})
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-take n stream
+Returns a newly-allocated stream containing the first @var{n} elements
+of the input @var{stream}. If the input @var{stream} has less than
+@var{n} elements, so does the output stream. See also
+@code{stream-drop}.
+@end deffn
+
+@deffn {Scheme Procedure} stream-take-while pred stream
+Takes a predicate and a @code{stream} and returns a newly-allocated
+stream containing those elements @code{x} that form the maximal prefix
+of the input stream which satisfy @var{pred}. See also
+@code{stream-drop-while}.
+@end deffn
+
+@deffn {Scheme Procedure} stream-unfold map pred gen base
+The fundamental recursive stream constructor. It constructs a stream by
+repeatedly applying @var{gen} to successive values of @var{base}, in the
+manner of @code{stream-iterate}, then applying @var{map} to each of the
+values so generated, appending each of the mapped values to the output
+stream as long as @code{(pred? base)} returns a true value. See also
+@code{stream-iterate} and @code{stream-unfolds}.
+
+The expression below creates the finite stream @samp{0 1 4 9 16 25 36 49
+64 81}. Initially the @var{base} is 0, which is less than 10, so
+@var{map} squares the @var{base} and the mapped value becomes the first
+element of the output stream. Then @var{gen} increments the @var{base}
+by 1, so it becomes 1; this is less than 10, so @var{map} squares the
+new @var{base} and 1 becomes the second element of the output stream.
+And so on, until the base becomes 10, when @var{pred} stops the
+recursion and stream-null ends the output stream.
+
+@example
+(stream-unfold
+ (lambda (x) (expt x 2)) ; map
+ (lambda (x) (< x 10)) ; pred?
+ (lambda (x) (+ x 1)) ; gen
+ 0) ; base
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-unfolds proc seed
+Returns @var{n} newly-allocated streams containing those elements
+produced by successive calls to the generator @var{proc}, which takes
+the current @var{seed} as its argument and returns @var{n}+1 values
+
+(@var{proc} @var{seed}) @result{} @var{seed} @var{result_0} @dots{} @var{result_n-1}
+
+where the returned @var{seed} is the input @var{seed} to the next call
+to the generator and @var{result_i} indicates how to produce the next
+element of the @var{i}th result stream:
+
+@itemize @bullet
+@item
+(@var{value}): @var{value} is the next car of the result stream.
+
+@item
+@code{#f}: no value produced by this iteration of the generator
+@var{proc} for the result stream.
+
+@item
+(): the end of the result stream.
+@end itemize
+
+It may require multiple calls of @var{proc} to produce the next element
+of any particular result stream. See also @code{stream-iterate} and
+@code{stream-unfold}.
+
+@example
+(define (stream-partition pred? strm)
+ (stream-unfolds
+ (lambda (s)
+ (if (stream-null? s)
+ (values s '() '())
+ (let ((a (stream-car s))
+ (d (stream-cdr s)))
+ (if (pred? a)
+ (values d (list a) #f)
+ (values d #f (list a))))))
+ strm))
+
+(call-with-values
+ (lambda ()
+ (stream-partition odd?
+ (stream-range 1 6)))
+ (lambda (odds evens)
+ (list (stream->list odds)
+ (stream->list evens))))
+ @result{} ((1 3 5) (2 4))
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} stream-zip stream @dots{}
+Returns a newly-allocated stream in which each element is a list (not a
+stream) of the corresponding elements of the input @var{stream}s. The
+output stream is as long as the shortest input @var{stream}, if any of
+the input @var{stream}s is finite, or is infinite if all the input
+@var{stream}s are infinite.
+@end deffn
+
+@node SRFI-42
+@subsection SRFI-42 - Eager Comprehensions
+@cindex SRFI-42
+
+See @uref{http://srfi.schemers.org/srfi-42/srfi-42.html, the
+specification of SRFI-42}.
+
+@node SRFI-43
+@subsection SRFI-43 - Vector Library
+@cindex SRFI-43
+
+This subsection is based on the
+@uref{http://srfi.schemers.org/srfi-43/srfi-43.html, specification of
+SRFI-43} by Taylor Campbell.
+
+@c The copyright notice and license text of the SRFI-43 specification is
+@c reproduced below:
+
+@c Copyright (C) Taylor Campbell (2003). All Rights Reserved.
+
+@c Permission is hereby granted, free of charge, to any person obtaining a
+@c copy of this software and associated documentation files (the
+@c "Software"), to deal in the Software without restriction, including
+@c without limitation the rights to use, copy, modify, merge, publish,
+@c distribute, sublicense, and/or sell copies of the Software, and to
+@c permit persons to whom the Software is furnished to do so, subject to
+@c the following conditions:
+
+@c The above copyright notice and this permission notice shall be included
+@c in all copies or substantial portions of the Software.
+
+@c THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+@c OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+@c MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+@c NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+@c LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+@c OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+@c WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+@noindent
+SRFI-43 implements a comprehensive library of vector operations. It can
+be made available with:
+
+@example
+(use-modules (srfi srfi-43))
+@end example
+
+@menu
+* SRFI-43 Constructors::
+* SRFI-43 Predicates::
+* SRFI-43 Selectors::
+* SRFI-43 Iteration::
+* SRFI-43 Searching::
+* SRFI-43 Mutators::
+* SRFI-43 Conversion::
+@end menu
+
+@node SRFI-43 Constructors
+@subsubsection SRFI-43 Constructors
+
+@deffn {Scheme Procedure} make-vector size [fill]
+Create and return a vector of size @var{size}, optionally filling it
+with @var{fill}. The default value of @var{fill} is unspecified.
+
+@example
+(make-vector 5 3) @result{} #(3 3 3 3 3)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector x @dots{}
+Create and return a vector whose elements are @var{x} @enddots{}.
+
+@example
+(vector 0 1 2 3 4) @result{} #(0 1 2 3 4)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-unfold f length initial-seed @dots{}
+The fundamental vector constructor. Create a vector whose length is
+@var{length} and iterates across each index k from 0 up to
+@var{length} - 1, applying @var{f} at each iteration to the current index
+and current seeds, in that order, to receive n + 1 values: first, the
+element to put in the kth slot of the new vector and n new seeds for
+the next iteration. It is an error for the number of seeds to vary
+between iterations.
+
+@example
+(vector-unfold (lambda (i x) (values x (- x 1)))
+ 10 0)
+@result{} #(0 -1 -2 -3 -4 -5 -6 -7 -8 -9)
+
+(vector-unfold values 10)
+@result{} #(0 1 2 3 4 5 6 7 8 9)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-unfold-right f length initial-seed @dots{}
+Like @code{vector-unfold}, but it uses @var{f} to generate elements from
+right-to-left, rather than left-to-right.
+
+@example
+(vector-unfold-right (lambda (i x) (values x (+ x 1)))
+ 10 0)
+@result{} #(9 8 7 6 5 4 3 2 1 0)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-copy vec [start [end [fill]]]
+Allocate a new vector whose length is @var{end} - @var{start} and fills
+it with elements from @var{vec}, taking elements from @var{vec} starting
+at index @var{start} and stopping at index @var{end}. @var{start}
+defaults to 0 and @var{end} defaults to the value of
+@code{(vector-length vec)}. If @var{end} extends beyond the length of
+@var{vec}, the slots in the new vector that obviously cannot be filled
+by elements from @var{vec} are filled with @var{fill}, whose default
+value is unspecified.
+
+@example
+(vector-copy '#(a b c d e f g h i))
+@result{} #(a b c d e f g h i)
+
+(vector-copy '#(a b c d e f g h i) 6)
+@result{} #(g h i)
+
+(vector-copy '#(a b c d e f g h i) 3 6)
+@result{} #(d e f)
+
+(vector-copy '#(a b c d e f g h i) 6 12 'x)
+@result{} #(g h i x x x)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-reverse-copy vec [start [end]]
+Like @code{vector-copy}, but it copies the elements in the reverse order
+from @var{vec}.
+
+@example
+(vector-reverse-copy '#(5 4 3 2 1 0) 1 5)
+@result{} #(1 2 3 4)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-append vec @dots{}
+Return a newly allocated vector that contains all elements in order from
+the subsequent locations in @var{vec} @enddots{}.
+
+@example
+(vector-append '#(a) '#(b c d))
+@result{} #(a b c d)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-concatenate list-of-vectors
+Append each vector in @var{list-of-vectors}. Equivalent to
+@code{(apply vector-append list-of-vectors)}.
+
+@example
+(vector-concatenate '(#(a b) #(c d)))
+@result{} #(a b c d)
+@end example
+@end deffn
+
+@node SRFI-43 Predicates
+@subsubsection SRFI-43 Predicates
+
+@deffn {Scheme Procedure} vector? obj
+Return true if @var{obj} is a vector, else return false.
+@end deffn
+
+@deffn {Scheme Procedure} vector-empty? vec
+Return true if @var{vec} is empty, i.e. its length is 0, else return
+false.
+@end deffn
+
+@deffn {Scheme Procedure} vector= elt=? vec @dots{}
+Return true if the vectors @var{vec} @dots{} have equal lengths and
+equal elements according to @var{elt=?}. @var{elt=?} is always applied
+to two arguments. Element comparison must be consistent with @code{eq?}
+in the following sense: if @code{(eq? a b)} returns true, then
+@code{(elt=? a b)} must also return true. The order in which
+comparisons are performed is unspecified.
+@end deffn
+
+@node SRFI-43 Selectors
+@subsubsection SRFI-43 Selectors
+
+@deffn {Scheme Procedure} vector-ref vec i
+Return the value that the location in @var{vec} at @var{i} is mapped to
+in the store. Indexing is based on zero.
+@end deffn
+
+@deffn {Scheme Procedure} vector-length vec
+Return the length of @var{vec}.
+@end deffn
+
+@node SRFI-43 Iteration
+@subsubsection SRFI-43 Iteration
+
+@deffn {Scheme Procedure} vector-fold kons knil vec1 vec2 @dots{}
+The fundamental vector iterator. @var{kons} is iterated over each index
+in all of the vectors, stopping at the end of the shortest; @var{kons}
+is applied as
+@smalllisp
+(kons i state (vector-ref vec1 i) (vector-ref vec2 i) ...)
+@end smalllisp
+where @var{state} is the current state value, and @var{i} is the current
+index. The current state value begins with @var{knil}, and becomes
+whatever @var{kons} returned at the respective iteration. The iteration
+is strictly left-to-right.
+@end deffn
+
+@deffn {Scheme Procedure} vector-fold-right kons knil vec1 vec2 @dots{}
+Similar to @code{vector-fold}, but it iterates right-to-left instead of
+left-to-right.
+@end deffn
+
+@deffn {Scheme Procedure} vector-map f vec1 vec2 @dots{}
+Return a new vector of the shortest size of the vector arguments. Each
+element at index i of the new vector is mapped from the old vectors by
+@smalllisp
+(f i (vector-ref vec1 i) (vector-ref vec2 i) ...)
+@end smalllisp
+The dynamic order of application of @var{f} is unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} vector-map! f vec1 vec2 @dots{}
+Similar to @code{vector-map}, but rather than mapping the new elements
+into a new vector, the new mapped elements are destructively inserted
+into @var{vec1}. The dynamic order of application of @var{f} is
+unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} vector-for-each f vec1 vec2 @dots{}
+Call @code{(f i (vector-ref vec1 i) (vector-ref vec2 i) ...)} for each
+index i less than the length of the shortest vector passed. The
+iteration is strictly left-to-right.
+@end deffn
+
+@deffn {Scheme Procedure} vector-count pred? vec1 vec2 @dots{}
+Count the number of parallel elements in the vectors that satisfy
+@var{pred?}, which is applied, for each index i less than the length of
+the smallest vector, to i and each parallel element in the vectors at
+that index, in order.
+
+@example
+(vector-count (lambda (i elt) (even? elt))
+ '#(3 1 4 1 5 9 2 5 6))
+@result{} 3
+(vector-count (lambda (i x y) (< x y))
+ '#(1 3 6 9) '#(2 4 6 8 10 12))
+@result{} 2
+@end example
+@end deffn
+
+@node SRFI-43 Searching
+@subsubsection SRFI-43 Searching
+
+@deffn {Scheme Procedure} vector-index pred? vec1 vec2 @dots{}
+Find and return the index of the first elements in @var{vec1} @var{vec2}
+@dots{} that satisfy @var{pred?}. If no matching element is found by
+the end of the shortest vector, return @code{#f}.
+
+@example
+(vector-index even? '#(3 1 4 1 5 9))
+@result{} 2
+(vector-index < '#(3 1 4 1 5 9 2 5 6) '#(2 7 1 8 2))
+@result{} 1
+(vector-index = '#(3 1 4 1 5 9 2 5 6) '#(2 7 1 8 2))
+@result{} #f
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-index-right pred? vec1 vec2 @dots{}
+Like @code{vector-index}, but it searches right-to-left, rather than
+left-to-right. Note that the SRFI 43 specification requires that all
+the vectors must have the same length, but both the SRFI 43 reference
+implementation and Guile's implementation allow vectors with unequal
+lengths, and start searching from the last index of the shortest vector.
+@end deffn
+
+@deffn {Scheme Procedure} vector-skip pred? vec1 vec2 @dots{}
+Find and return the index of the first elements in @var{vec1} @var{vec2}
+@dots{} that do not satisfy @var{pred?}. If no matching element is
+found by the end of the shortest vector, return @code{#f}. Equivalent
+to @code{vector-index} but with the predicate inverted.
+
+@example
+(vector-skip number? '#(1 2 a b 3 4 c d)) @result{} 2
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-skip-right pred? vec1 vec2 @dots{}
+Like @code{vector-skip}, but it searches for a non-matching element
+right-to-left, rather than left-to-right. Note that the SRFI 43
+specification requires that all the vectors must have the same length,
+but both the SRFI 43 reference implementation and Guile's implementation
+allow vectors with unequal lengths, and start searching from the last
+index of the shortest vector.
+@end deffn
+
+@deffn {Scheme Procedure} vector-binary-search vec value cmp [start [end]]
+Find and return an index of @var{vec} between @var{start} and @var{end}
+whose value is @var{value} using a binary search. If no matching
+element is found, return @code{#f}. The default @var{start} is 0 and
+the default @var{end} is the length of @var{vec}.
+
+@var{cmp} must be a procedure of two arguments such that @code{(cmp a
+b)} returns a negative integer if @math{a < b}, a positive integer if
+@math{a > b}, or zero if @math{a = b}. The elements of @var{vec} must
+be sorted in non-decreasing order according to @var{cmp}.
+
+Note that SRFI 43 does not document the @var{start} and @var{end}
+arguments, but both its reference implementation and Guile's
+implementation support them.
+
+@example
+(define (char-cmp c1 c2)
+ (cond ((char<? c1 c2) -1)
+ ((char>? c1 c2) 1)
+ (else 0)))
+
+(vector-binary-search '#(#\a #\b #\c #\d #\e #\f #\g #\h)
+ #\g
+ char-cmp)
+@result{} 6
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} vector-any pred? vec1 vec2 @dots{}
+Find the first parallel set of elements from @var{vec1} @var{vec2}
+@dots{} for which @var{pred?} returns a true value. If such a parallel
+set of elements exists, @code{vector-any} returns the value that
+@var{pred?} returned for that set of elements. The iteration is
+strictly left-to-right.
+@end deffn
+
+@deffn {Scheme Procedure} vector-every pred? vec1 vec2 @dots{}
+If, for every index i between 0 and the length of the shortest vector
+argument, the set of elements @code{(vector-ref vec1 i)}
+@code{(vector-ref vec2 i)} @dots{} satisfies @var{pred?},
+@code{vector-every} returns the value that @var{pred?} returned for the
+last set of elements, at the last index of the shortest vector.
+Otherwise it returns @code{#f}. The iteration is strictly
+left-to-right.
+@end deffn
+
+@node SRFI-43 Mutators
+@subsubsection SRFI-43 Mutators
+
+@deffn {Scheme Procedure} vector-set! vec i value
+Assign the contents of the location at @var{i} in @var{vec} to
+@var{value}.
+@end deffn
+
+@deffn {Scheme Procedure} vector-swap! vec i j
+Swap the values of the locations in @var{vec} at @var{i} and @var{j}.
+@end deffn
+
+@deffn {Scheme Procedure} vector-fill! vec fill [start [end]]
+Assign the value of every location in @var{vec} between @var{start} and
+@var{end} to @var{fill}. @var{start} defaults to 0 and @var{end}
+defaults to the length of @var{vec}.
+@end deffn
+
+@deffn {Scheme Procedure} vector-reverse! vec [start [end]]
+Destructively reverse the contents of @var{vec} between @var{start} and
+@var{end}. @var{start} defaults to 0 and @var{end} defaults to the
+length of @var{vec}.
+@end deffn
+
+@deffn {Scheme Procedure} vector-copy! target tstart source [sstart [send]]
+Copy a block of elements from @var{source} to @var{target}, both of
+which must be vectors, starting in @var{target} at @var{tstart} and
+starting in @var{source} at @var{sstart}, ending when (@var{send} -
+@var{sstart}) elements have been copied. It is an error for
+@var{target} to have a length less than (@var{tstart} + @var{send} -
+@var{sstart}). @var{sstart} defaults to 0 and @var{send} defaults to
+the length of @var{source}.
+@end deffn
+
+@deffn {Scheme Procedure} vector-reverse-copy! target tstart source [sstart [send]]
+Like @code{vector-copy!}, but this copies the elements in the reverse
+order. It is an error if @var{target} and @var{source} are identical
+vectors and the @var{target} and @var{source} ranges overlap; however,
+if @var{tstart} = @var{sstart}, @code{vector-reverse-copy!} behaves as
+@code{(vector-reverse! target tstart send)} would.
+@end deffn
+
+@node SRFI-43 Conversion
+@subsubsection SRFI-43 Conversion
+
+@deffn {Scheme Procedure} vector->list vec [start [end]]
+Return a newly allocated list containing the elements in @var{vec}
+between @var{start} and @var{end}. @var{start} defaults to 0 and
+@var{end} defaults to the length of @var{vec}.
+@end deffn
+
+@deffn {Scheme Procedure} reverse-vector->list vec [start [end]]
+Like @code{vector->list}, but the resulting list contains the specified
+range of elements of @var{vec} in reverse order.
+@end deffn
+
+@deffn {Scheme Procedure} list->vector proper-list [start [end]]
+Return a newly allocated vector of the elements from @var{proper-list}
+with indices between @var{start} and @var{end}. @var{start} defaults to
+0 and @var{end} defaults to the length of @var{proper-list}. Note that
+SRFI 43 does not document the @var{start} and @var{end} arguments, but
+both its reference implementation and Guile's implementation support
+them.
+@end deffn
+
+@deffn {Scheme Procedure} reverse-list->vector proper-list [start [end]]
+Like @code{list->vector}, but the resulting vector contains the specified
+range of elements of @var{proper-list} in reverse order. Note that SRFI
+43 does not document the @var{start} and @var{end} arguments, but both
+its reference implementation and Guile's implementation support them.
+@end deffn
+
+@node SRFI-45
+@subsection SRFI-45 - Primitives for Expressing Iterative Lazy Algorithms
+@cindex SRFI-45
+
+This subsection is based on @uref{http://srfi.schemers.org/srfi-45/srfi-45.html, the
+specification of SRFI-45} written by Andr@'e van Tonder.
+
+@c Copyright (C) André van Tonder (2003). All Rights Reserved.
+
+@c Permission is hereby granted, free of charge, to any person obtaining a
+@c copy of this software and associated documentation files (the
+@c "Software"), to deal in the Software without restriction, including
+@c without limitation the rights to use, copy, modify, merge, publish,
+@c distribute, sublicense, and/or sell copies of the Software, and to
+@c permit persons to whom the Software is furnished to do so, subject to
+@c the following conditions:
+
+@c The above copyright notice and this permission notice shall be included
+@c in all copies or substantial portions of the Software.
+
+@c THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+@c OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+@c MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+@c NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+@c LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+@c OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+@c WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+Lazy evaluation is traditionally simulated in Scheme using @code{delay}
+and @code{force}. However, these primitives are not powerful enough to
+express a large class of lazy algorithms that are iterative. Indeed, it
+is folklore in the Scheme community that typical iterative lazy
+algorithms written using delay and force will often require unbounded
+memory.
+
+This SRFI provides set of three operations: @{@code{lazy}, @code{delay},
+@code{force}@}, which allow the programmer to succinctly express lazy
+algorithms while retaining bounded space behavior in cases that are
+properly tail-recursive. A general recipe for using these primitives is
+provided. An additional procedure @code{eager} is provided for the
+construction of eager promises in cases where efficiency is a concern.
+
+Although this SRFI redefines @code{delay} and @code{force}, the
+extension is conservative in the sense that the semantics of the subset
+@{@code{delay}, @code{force}@} in isolation (i.e., as long as the
+program does not use @code{lazy}) agrees with that in R5RS. In other
+words, no program that uses the R5RS definitions of delay and force will
+break if those definition are replaced by the SRFI-45 definitions of
+delay and force.
+
+Guile also adds @code{promise?} to the list of exports, which is not
+part of the official SRFI-45.
+
+@deffn {Scheme Procedure} promise? obj
+Return true if @var{obj} is an SRFI-45 promise, otherwise return false.
+@end deffn
+
+@deffn {Scheme Syntax} delay expression
+Takes an expression of arbitrary type @var{a} and returns a promise of
+type @code{(Promise @var{a})} which at some point in the future may be
+asked (by the @code{force} procedure) to evaluate the expression and
+deliver the resulting value.
+@end deffn
+
+@deffn {Scheme Syntax} lazy expression
+Takes an expression of type @code{(Promise @var{a})} and returns a
+promise of type @code{(Promise @var{a})} which at some point in the
+future may be asked (by the @code{force} procedure) to evaluate the
+expression and deliver the resulting promise.
+@end deffn
+
+@deffn {Scheme Procedure} force expression
+Takes an argument of type @code{(Promise @var{a})} and returns a value
+of type @var{a} as follows: If a value of type @var{a} has been computed
+for the promise, this value is returned. Otherwise, the promise is
+first evaluated, then overwritten by the obtained promise or value, and
+then force is again applied (iteratively) to the promise.
+@end deffn
+
+@deffn {Scheme Procedure} eager expression
+Takes an argument of type @var{a} and returns a value of type
+@code{(Promise @var{a})}. As opposed to @code{delay}, the argument is
+evaluated eagerly. Semantically, writing @code{(eager expression)} is
+equivalent to writing
+
+@lisp
+(let ((value expression)) (delay value)).
+@end lisp
+
+However, the former is more efficient since it does not require
+unnecessary creation and evaluation of thunks. We also have the
+equivalence
+
+@lisp
+(delay expression) = (lazy (eager expression))
+@end lisp
+@end deffn
+
+The following reduction rules may be helpful for reasoning about these
+primitives. However, they do not express the memoization and memory
+usage semantics specified above:
+
+@lisp
+(force (delay expression)) -> expression
+(force (lazy expression)) -> (force expression)
+(force (eager value)) -> value
+@end lisp
+
+@subsubheading Correct usage
+
+We now provide a general recipe for using the primitives @{@code{lazy},
+@code{delay}, @code{force}@} to express lazy algorithms in Scheme. The
+transformation is best described by way of an example: Consider the
+stream-filter algorithm, expressed in a hypothetical lazy language as
+
+@lisp
+(define (stream-filter p? s)
+ (if (null? s) '()
+ (let ((h (car s))
+ (t (cdr s)))
+ (if (p? h)
+ (cons h (stream-filter p? t))
+ (stream-filter p? t)))))
+@end lisp
+
+This algorithm can be expressed as follows in Scheme:
+
+@lisp
+(define (stream-filter p? s)
+ (lazy
+ (if (null? (force s)) (delay '())
+ (let ((h (car (force s)))
+ (t (cdr (force s))))
+ (if (p? h)
+ (delay (cons h (stream-filter p? t)))
+ (stream-filter p? t))))))
+@end lisp
+
+In other words, we
+
+@itemize @bullet
+@item
+wrap all constructors (e.g., @code{'()}, @code{cons}) with @code{delay},
+@item
+apply @code{force} to arguments of deconstructors (e.g., @code{car},
+@code{cdr} and @code{null?}),
+@item
+wrap procedure bodies with @code{(lazy ...)}.
+@end itemize
+
+@node SRFI-46
+@subsection SRFI-46 Basic syntax-rules Extensions
+@cindex SRFI-46
+
+Guile's core @code{syntax-rules} supports the extensions specified by
+SRFI-46/R7RS. Tail patterns have been supported since at least Guile
+2.0, and custom ellipsis identifiers have been supported since Guile
+2.0.10. @xref{Syntax Rules}.
+
+@node SRFI-55
+@subsection SRFI-55 - Requiring Features
+@cindex SRFI-55
+
+SRFI-55 provides @code{require-extension} which is a portable
+mechanism to load selected SRFI modules. This is implemented in the
+Guile core, there's no module needed to get SRFI-55 itself.
+
+@deffn {library syntax} require-extension clause1 clause2 @dots{}
+Require the features of @var{clause1} @var{clause2} @dots{} , throwing
+an error if any are unavailable.
+
+A @var{clause} is of the form @code{(@var{identifier} arg...)}. The
+only @var{identifier} currently supported is @code{srfi} and the
+arguments are SRFI numbers. For example to get SRFI-1 and SRFI-6,
+
+@example
+(require-extension (srfi 1 6))
+@end example
+
+@code{require-extension} can only be used at the top-level.
+
+A Guile-specific program can simply @code{use-modules} to load SRFIs
+not already in the core, @code{require-extension} is for programs
+designed to be portable to other Scheme implementations.
+@end deffn
+
+
+@node SRFI-60
+@subsection SRFI-60 - Integers as Bits
+@cindex SRFI-60
+@cindex integers as bits
+@cindex bitwise logical
+
+This SRFI provides various functions for treating integers as bits and
+for bitwise manipulations. These functions can be obtained with,
+
+@example
+(use-modules (srfi srfi-60))
+@end example
+
+Integers are treated as infinite precision twos-complement, the same
+as in the core logical functions (@pxref{Bitwise Operations}). And
+likewise bit indexes start from 0 for the least significant bit. The
+following functions in this SRFI are already in the Guile core,
+
+@quotation
+@code{logand},
+@code{logior},
+@code{logxor},
+@code{lognot},
+@code{logtest},
+@code{logcount},
+@code{integer-length},
+@code{logbit?},
+@code{ash}
+@end quotation
+
+@sp 1
+@defun bitwise-and n1 ...
+@defunx bitwise-ior n1 ...
+@defunx bitwise-xor n1 ...
+@defunx bitwise-not n
+@defunx any-bits-set? j k
+@defunx bit-set? index n
+@defunx arithmetic-shift n count
+@defunx bit-field n start end
+@defunx bit-count n
+Aliases for @code{logand}, @code{logior}, @code{logxor},
+@code{lognot}, @code{logtest}, @code{logbit?}, @code{ash},
+@code{bit-extract} and @code{logcount} respectively.
Note that the name @code{bit-count} conflicts with @code{bit-count} in
the core (@pxref{Bit Vectors}).
return multiple values, as well as arbitrary definitions of test
success. SRFI 61 is implemented in the Guile core; there's no module
needed to get SRFI-61 itself. Extended @code{cond} is documented in
-@ref{if cond case,, Simple Conditional Evaluation}.
+@ref{Conditionals,, Simple Conditional Evaluation}.
+
+@node SRFI-62
+@subsection SRFI-62 - S-expression comments.
+@cindex SRFI-62
+
+Starting from version 2.0, Guile's @code{read} supports SRFI-62/R7RS
+S-expression comments by default.
+
+@node SRFI-64
+@subsection SRFI-64 - A Scheme API for test suites.
+@cindex SRFI-64
+
+See @uref{http://srfi.schemers.org/srfi-64/srfi-64.html, the
+specification of SRFI-64}.
+@node SRFI-67
+@subsection SRFI-67 - Compare procedures
+@cindex SRFI-67
+
+See @uref{http://srfi.schemers.org/srfi-67/srfi-67.html, the
+specification of SRFI-67}.
@node SRFI-69
@subsection SRFI-69 - Basic hash tables
@code{hash} is a backwards-compatible replacement for Guile's built-in
@code{hash}.
+@node SRFI-87
+@subsection SRFI-87 => in case clauses
+@cindex SRFI-87
+
+Starting from version 2.0.6, Guile's core @code{case} syntax supports
+@code{=>} in clauses, as specified by SRFI-87/R7RS.
+@xref{Conditionals}.
+
@node SRFI-88
@subsection SRFI-88 Keyword Objects
@cindex SRFI-88
@dfn{keyword objects}, which are equivalent to Guile's keywords
(@pxref{Keywords}). SRFI-88 keywords can be entered using the
@dfn{postfix keyword syntax}, which consists of an identifier followed
-by @code{:} (@pxref{Reader options, @code{postfix} keyword syntax}).
+by @code{:} (@pxref{Scheme Read, @code{postfix} keyword syntax}).
SRFI-88 can be made available with:
@example
association list in which both the keys and the values are strings.
@end deffn
+@node SRFI-105
+@subsection SRFI-105 Curly-infix expressions.
+@cindex SRFI-105
+@cindex curly-infix
+@cindex curly-infix-and-bracket-lists
+
+Guile's built-in reader includes support for SRFI-105 curly-infix
+expressions. See @uref{http://srfi.schemers.org/srfi-105/srfi-105.html,
+the specification of SRFI-105}. Some examples:
+
+@example
+@{n <= 5@} @result{} (<= n 5)
+@{a + b + c@} @result{} (+ a b c)
+@{a * @{b + c@}@} @result{} (* a (+ b c))
+@{(- a) / b@} @result{} (/ (- a) b)
+@{-(a) / b@} @result{} (/ (- a) b) as well
+@{(f a b) + (g h)@} @result{} (+ (f a b) (g h))
+@{f(a b) + g(h)@} @result{} (+ (f a b) (g h)) as well
+@{f[a b] + g(h)@} @result{} (+ ($bracket-apply$ f a b) (g h))
+'@{a + f(b) + x@} @result{} '(+ a (f b) x)
+@{length(x) >= 6@} @result{} (>= (length x) 6)
+@{n-1 + n-2@} @result{} (+ n-1 n-2)
+@{n * factorial@{n - 1@}@} @result{} (* n (factorial (- n 1)))
+@{@{a > 0@} and @{b >= 1@}@} @result{} (and (> a 0) (>= b 1))
+@{f@{n - 1@}(x)@} @result{} ((f (- n 1)) x)
+@{a . z@} @result{} ($nfx$ a . z)
+@{a + b - c@} @result{} ($nfx$ a + b - c)
+@end example
+
+To enable curly-infix expressions within a file, place the reader
+directive @code{#!curly-infix} before the first use of curly-infix
+notation. To globally enable curly-infix expressions in Guile's reader,
+set the @code{curly-infix} read option.
+
+Guile also implements the following non-standard extension to SRFI-105:
+if @code{curly-infix} is enabled and there is no other meaning assigned
+to square brackets (i.e. the @code{square-brackets} read option is
+turned off), then lists within square brackets are read as normal lists
+but with the special symbol @code{$bracket-list$} added to the front.
+To enable this combination of read options within a file, use the reader
+directive @code{#!curly-infix-and-bracket-lists}. For example:
+
+@example
+[a b] @result{} ($bracket-list$ a b)
+[a . b] @result{} ($bracket-list$ a . b)
+@end example
+
+
+For more information on reader options, @xref{Scheme Read}.
+
+@node SRFI-111
+@subsection SRFI-111 Boxes.
+@cindex SRFI-111
+
+@uref{http://srfi.schemers.org/srfi-111/srfi-111.html, SRFI-111}
+provides boxes: objects with a single mutable cell.
+
+@deffn {Scheme Procedure} box value
+Return a newly allocated box whose contents is initialized to
+@var{value}.
+@end deffn
+
+@deffn {Scheme Procedure} box? obj
+Return true if @var{obj} is a box, otherwise return false.
+@end deffn
+
+@deffn {Scheme Procedure} unbox box
+Return the current contents of @var{box}.
+@end deffn
+
+@deffn {Scheme Procedure} set-box! box value
+Set the contents of @var{box} to @var{value}.
+@end deffn
+
@c srfi-modules.texi ends here
@c Local Variables:
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