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+@c -*-texinfo-*-
+@c This is part of the GNU Guile Reference Manual.
+@c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004
+@c Free Software Foundation, Inc.
+@c See the file guile.texi for copying conditions.
+
+@page
+@node Compound Data Types
+@section Compound Data Types
+
+This chapter describes Guile's compound data types. By @dfn{compound}
+we mean that the primary purpose of these data types is to act as
+containers for other kinds of data (including other compound objects).
+For instance, a (non-uniform) vector with length 5 is a container that
+can hold five arbitrary Scheme objects.
+
+The various kinds of container object differ from each other in how
+their memory is allocated, how they are indexed, and how particular
+values can be looked up within them.
+
+@menu
+* Pairs:: Scheme's basic building block.
+* Lists:: Special list functions supported by Guile.
+* Vectors:: One-dimensional arrays of Scheme objects.
+* Records::
+* Structures::
+* Arrays:: Arrays of values.
+* Dictionary Types:: About dictionary types in general.
+* Association Lists:: List-based dictionaries.
+* Hash Tables:: Table-based dictionaries.
+@end menu
+
+
+@node Pairs
+@subsection Pairs
+@tpindex Pairs
+
+Pairs are used to combine two Scheme objects into one compound object.
+Hence the name: A pair stores a pair of objects.
+
+The data type @dfn{pair} is extremely important in Scheme, just like in
+any other Lisp dialect. The reason is that pairs are not only used to
+make two values available as one object, but that pairs are used for
+constructing lists of values. Because lists are so important in Scheme,
+they are described in a section of their own (@pxref{Lists}).
+
+Pairs can literally get entered in source code or at the REPL, in the
+so-called @dfn{dotted list} syntax. This syntax consists of an opening
+parentheses, the first element of the pair, a dot, the second element
+and a closing parentheses. The following example shows how a pair
+consisting of the two numbers 1 and 2, and a pair containing the symbols
+@code{foo} and @code{bar} can be entered. It is very important to write
+the whitespace before and after the dot, because otherwise the Scheme
+parser would not be able to figure out where to split the tokens.
+
+@lisp
+(1 . 2)
+(foo . bar)
+@end lisp
+
+But beware, if you want to try out these examples, you have to
+@dfn{quote} the expressions. More information about quotation is
+available in the section (REFFIXME). The correct way to try these
+examples is as follows.
+
+@lisp
+'(1 . 2)
+@result{}
+(1 . 2)
+'(foo . bar)
+@result{}
+(foo . bar)
+@end lisp
+
+A new pair is made by calling the procedure @code{cons} with two
+arguments. Then the argument values are stored into a newly allocated
+pair, and the pair is returned. The name @code{cons} stands for
+"construct". Use the procedure @code{pair?} to test whether a
+given Scheme object is a pair or not.
+
+@rnindex cons
+@deffn {Scheme Procedure} cons x y
+@deffnx {C Function} scm_cons (x, y)
+Return a newly allocated pair whose car is @var{x} and whose
+cdr is @var{y}. The pair is guaranteed to be different (in the
+sense of @code{eq?}) from every previously existing object.
+@end deffn
+
+@rnindex pair?
+@deffn {Scheme Procedure} pair? x
+@deffnx {C Function} scm_pair_p (x)
+Return @code{#t} if @var{x} is a pair; otherwise return
+@code{#f}.
+@end deffn
+
+The two parts of a pair are traditionally called @dfn{car} and
+@dfn{cdr}. They can be retrieved with procedures of the same name
+(@code{car} and @code{cdr}), and can be modified with the procedures
+@code{set-car!} and @code{set-cdr!}. Since a very common operation in
+Scheme programs is to access the car of a pair, or the car of the cdr of
+a pair, etc., the procedures called @code{caar}, @code{cadr} and so on
+are also predefined.
+
+@rnindex car
+@rnindex cdr
+@deffn {Scheme Procedure} car pair
+@deffnx {Scheme Procedure} cdr pair
+Return the car or the cdr of @var{pair}, respectively.
+@end deffn
+
+@deffn {Scheme Procedure} caar pair
+@deffnx {Scheme Procedure} cadr pair @dots{}
+@deffnx {Scheme Procedure} cdddar pair
+@deffnx {Scheme Procedure} cddddr pair
+These procedures are compositions of @code{car} and @code{cdr}, where
+for example @code{caddr} could be defined by
+
+@lisp
+(define caddr (lambda (x) (car (cdr (cdr x)))))
+@end lisp
+@end deffn
+
+@rnindex set-car!
+@deffn {Scheme Procedure} set-car! pair value
+@deffnx {C Function} scm_set_car_x (pair, value)
+Stores @var{value} in the car field of @var{pair}. The value returned
+by @code{set-car!} is unspecified.
+@end deffn
+
+@rnindex set-cdr!
+@deffn {Scheme Procedure} set-cdr! pair value
+@deffnx {C Function} scm_set_cdr_x (pair, value)
+Stores @var{value} in the cdr field of @var{pair}. The value returned
+by @code{set-cdr!} is unspecified.
+@end deffn
+
+
+@node Lists
+@subsection Lists
+@tpindex Lists
+
+A very important data type in Scheme---as well as in all other Lisp
+dialects---is the data type @dfn{list}.@footnote{Strictly speaking,
+Scheme does not have a real datatype @dfn{list}. Lists are made up of
+@dfn{chained pairs}, and only exist by definition---a list is a chain
+of pairs which looks like a list.}
+
+This is the short definition of what a list is:
+
+@itemize @bullet
+@item
+Either the empty list @code{()},
+
+@item
+or a pair which has a list in its cdr.
+@end itemize
+
+@c FIXME::martin: Describe the pair chaining in more detail.
+
+@c FIXME::martin: What is a proper, what an improper list?
+@c What is a circular list?
+
+@c FIXME::martin: Maybe steal some graphics from the Elisp reference
+@c manual?
+
+@menu
+* List Syntax:: Writing literal lists.
+* List Predicates:: Testing lists.
+* List Constructors:: Creating new lists.
+* List Selection:: Selecting from lists, getting their length.
+* Append/Reverse:: Appending and reversing lists.
+* List Modification:: Modifying existing lists.
+* List Searching:: Searching for list elements
+* List Mapping:: Applying procedures to lists.
+@end menu
+
+@node List Syntax
+@subsubsection List Read Syntax
+
+The syntax for lists is an opening parentheses, then all the elements of
+the list (separated by whitespace) and finally a closing
+parentheses.@footnote{Note that there is no separation character between
+the list elements, like a comma or a semicolon.}.
+
+@lisp
+(1 2 3) ; @r{a list of the numbers 1, 2 and 3}
+("foo" bar 3.1415) ; @r{a string, a symbol and a real number}
+() ; @r{the empty list}
+@end lisp
+
+The last example needs a bit more explanation. A list with no elements,
+called the @dfn{empty list}, is special in some ways. It is used for
+terminating lists by storing it into the cdr of the last pair that makes
+up a list. An example will clear that up:
+
+@lisp
+(car '(1))
+@result{}
+1
+(cdr '(1))
+@result{}
+()
+@end lisp
+
+This example also shows that lists have to be quoted (REFFIXME) when
+written, because they would otherwise be mistakingly taken as procedure
+applications (@pxref{Simple Invocation}).
+
+
+@node List Predicates
+@subsubsection List Predicates
+
+Often it is useful to test whether a given Scheme object is a list or
+not. List-processing procedures could use this information to test
+whether their input is valid, or they could do different things
+depending on the datatype of their arguments.
+
+@rnindex list?
+@deffn {Scheme Procedure} list? x
+@deffnx {C Function} scm_list_p (x)
+Return @code{#t} iff @var{x} is a proper list, else @code{#f}.
+@end deffn
+
+The predicate @code{null?} is often used in list-processing code to
+tell whether a given list has run out of elements. That is, a loop
+somehow deals with the elements of a list until the list satisfies
+@code{null?}. Then, the algorithm terminates.
+
+@rnindex null?
+@deffn {Scheme Procedure} null? x
+@deffnx {C Function} scm_null_p (x)
+Return @code{#t} iff @var{x} is the empty list, else @code{#f}.
+@end deffn
+
+@node List Constructors
+@subsubsection List Constructors
+
+This section describes the procedures for constructing new lists.
+@code{list} simply returns a list where the elements are the arguments,
+@code{cons*} is similar, but the last argument is stored in the cdr of
+the last pair of the list.
+
+@c C Function scm_list(rest) used to be documented here, but it's a
+@c no-op since it does nothing but return the list the caller must
+@c have already created.
+@c
+@deffn {Scheme Procedure} list elem1 @dots{} elemN
+@deffnx {C Function} scm_list_1 (elem1)
+@deffnx {C Function} scm_list_2 (elem1, elem2)
+@deffnx {C Function} scm_list_3 (elem1, elem2, elem3)
+@deffnx {C Function} scm_list_4 (elem1, elem2, elem3, elem4)
+@deffnx {C Function} scm_list_5 (elem1, elem2, elem3, elem4, elem5)
+@deffnx {C Function} scm_list_n (elem1, @dots{}, elemN, @nicode{SCM_UNDEFINED})
+@rnindex list
+Return a new list containing elements @var{elem1} to @var{elemN}.
+
+@code{scm_list_n} takes a variable number of arguments, terminated by
+the special @code{SCM_UNDEFINED}. That final @code{SCM_UNDEFINED} is
+not included in the list. None of @var{elem1} to @var{elemN} can
+themselves be @code{SCM_UNDEFINED}, or @code{scm_list_n} will
+terminate at that point.
+@end deffn
+
+@c C Function scm_cons_star(arg1,rest) used to be documented here,
+@c but it's not really a useful interface, since it expects the
+@c caller to have already consed up all but the first argument
+@c already.
+@c
+@deffn {Scheme Procedure} cons* arg1 arg2 @dots{}
+Like @code{list}, but the last arg provides the tail of the
+constructed list, returning @code{(cons @var{arg1} (cons
+@var{arg2} (cons @dots{} @var{argn})))}. Requires at least one
+argument. If given one argument, that argument is returned as
+result. This function is called @code{list*} in some other
+Schemes and in Common LISP.
+@end deffn
+
+@deffn {Scheme Procedure} list-copy lst
+@deffnx {C Function} scm_list_copy (lst)
+Return a (newly-created) copy of @var{lst}.
+@end deffn
+
+@deffn {Scheme Procedure} make-list n [init]
+Create a list containing of @var{n} elements, where each element is
+initialized to @var{init}. @var{init} defaults to the empty list
+@code{()} if not given.
+@end deffn
+
+Note that @code{list-copy} only makes a copy of the pairs which make up
+the spine of the lists. The list elements are not copied, which means
+that modifying the elements of the new list also modifies the elements
+of the old list. On the other hand, applying procedures like
+@code{set-cdr!} or @code{delv!} to the new list will not alter the old
+list. If you also need to copy the list elements (making a deep copy),
+use the procedure @code{copy-tree} (@pxref{Copying}).
+
+@node List Selection
+@subsubsection List Selection
+
+These procedures are used to get some information about a list, or to
+retrieve one or more elements of a list.
+
+@rnindex length
+@deffn {Scheme Procedure} length lst
+@deffnx {C Function} scm_length (lst)
+Return the number of elements in list @var{lst}.
+@end deffn
+
+@deffn {Scheme Procedure} last-pair lst
+@deffnx {C Function} scm_last_pair (lst)
+Return a pointer to the last pair in @var{lst}, signalling an error if
+@var{lst} is circular.
+@end deffn
+
+@rnindex list-ref
+@deffn {Scheme Procedure} list-ref list k
+@deffnx {C Function} scm_list_ref (list, k)
+Return the @var{k}th element from @var{list}.
+@end deffn
+
+@rnindex list-tail
+@deffn {Scheme Procedure} list-tail lst k
+@deffnx {Scheme Procedure} list-cdr-ref lst k
+@deffnx {C Function} scm_list_tail (lst, k)
+Return the "tail" of @var{lst} beginning with its @var{k}th element.
+The first element of the list is considered to be element 0.
+
+@code{list-tail} and @code{list-cdr-ref} are identical. It may help to
+think of @code{list-cdr-ref} as accessing the @var{k}th cdr of the list,
+or returning the results of cdring @var{k} times down @var{lst}.
+@end deffn
+
+@deffn {Scheme Procedure} list-head lst k
+@deffnx {C Function} scm_list_head (lst, k)
+Copy the first @var{k} elements from @var{lst} into a new list, and
+return it.
+@end deffn
+
+@node Append/Reverse
+@subsubsection Append and Reverse
+
+@code{append} and @code{append!} are used to concatenate two or more
+lists in order to form a new list. @code{reverse} and @code{reverse!}
+return lists with the same elements as their arguments, but in reverse
+order. The procedure variants with an @code{!} directly modify the
+pairs which form the list, whereas the other procedures create new
+pairs. This is why you should be careful when using the side-effecting
+variants.
+
+@rnindex append
+@deffn {Scheme Procedure} append lst1 @dots{} lstN
+@deffnx {Scheme Procedure} append! lst1 @dots{} lstN
+@deffnx {C Function} scm_append (lstlst)
+@deffnx {C Function} scm_append_x (lstlst)
+Return a list comprising all the elements of lists @var{lst1} to
+@var{lstN}.
+
+@lisp
+(append '(x) '(y)) @result{} (x y)
+(append '(a) '(b c d)) @result{} (a b c d)
+(append '(a (b)) '((c))) @result{} (a (b) (c))
+@end lisp
+
+The last argument @var{lstN} may actually be any object; an improper
+list results if the last argument is not a proper list.
+
+@lisp
+(append '(a b) '(c . d)) @result{} (a b c . d)
+(append '() 'a) @result{} a
+@end lisp
+
+@code{append} doesn't modify the given lists, but the return may share
+structure with the final @var{lstN}. @code{append!} modifies the
+given lists to form its return.
+
+For @code{scm_append} and @code{scm_append_x}, @var{lstlst} is a list
+of the list operands @var{lst1} @dots{} @var{lstN}. That @var{lstlst}
+itself is not modified or used in the return.
+@end deffn
+
+@rnindex reverse
+@deffn {Scheme Procedure} reverse lst
+@deffnx {Scheme Procedure} reverse! lst [newtail]
+@deffnx {C Function} scm_reverse (lst)
+@deffnx {C Function} scm_reverse_x (lst, newtail)
+Return a list comprising the elements of @var{lst}, in reverse order.
+
+@code{reverse} constructs a new list, @code{reverse!} modifies
+@var{lst} in constructing its return.
+
+For @code{reverse!}, the optional @var{newtail} is appended to to the
+result. @var{newtail} isn't reversed, it simply becomes the list
+tail. For @code{scm_reverse_x}, the @var{newtail} parameter is
+mandatory, but can be @code{SCM_EOL} if no further tail is required.
+@end deffn
+
+@node List Modification
+@subsubsection List Modification
+
+The following procedures modify an existing list, either by changing
+elements of the list, or by changing the list structure itself.
+
+@deffn {Scheme Procedure} list-set! list k val
+@deffnx {C Function} scm_list_set_x (list, k, val)
+Set the @var{k}th element of @var{list} to @var{val}.
+@end deffn
+
+@deffn {Scheme Procedure} list-cdr-set! list k val
+@deffnx {C Function} scm_list_cdr_set_x (list, k, val)
+Set the @var{k}th cdr of @var{list} to @var{val}.
+@end deffn
+
+@deffn {Scheme Procedure} delq item lst
+@deffnx {C Function} scm_delq (item, lst)
+Return a newly-created copy of @var{lst} with elements
+@code{eq?} to @var{item} removed. This procedure mirrors
+@code{memq}: @code{delq} compares elements of @var{lst} against
+@var{item} with @code{eq?}.
+@end deffn
+
+@deffn {Scheme Procedure} delv item lst
+@deffnx {C Function} scm_delv (item, lst)
+Return a newly-created copy of @var{lst} with elements
+@code{eqv?} to @var{item} removed. This procedure mirrors
+@code{memv}: @code{delv} compares elements of @var{lst} against
+@var{item} with @code{eqv?}.
+@end deffn
+
+@deffn {Scheme Procedure} delete item lst
+@deffnx {C Function} scm_delete (item, lst)
+Return a newly-created copy of @var{lst} with elements
+@code{equal?} to @var{item} removed. This procedure mirrors
+@code{member}: @code{delete} compares elements of @var{lst}
+against @var{item} with @code{equal?}.
+@end deffn
+
+@deffn {Scheme Procedure} delq! item lst
+@deffnx {Scheme Procedure} delv! item lst
+@deffnx {Scheme Procedure} delete! item lst
+@deffnx {C Function} scm_delq_x (item, lst)
+@deffnx {C Function} scm_delv_x (item, lst)
+@deffnx {C Function} scm_delete_x (item, lst)
+These procedures are destructive versions of @code{delq}, @code{delv}
+and @code{delete}: they modify the pointers in the existing @var{lst}
+rather than creating a new list. Caveat evaluator: Like other
+destructive list functions, these functions cannot modify the binding of
+@var{lst}, and so cannot be used to delete the first element of
+@var{lst} destructively.
+@end deffn
+
+@deffn {Scheme Procedure} delq1! item lst
+@deffnx {C Function} scm_delq1_x (item, lst)
+Like @code{delq!}, but only deletes the first occurrence of
+@var{item} from @var{lst}. Tests for equality using
+@code{eq?}. See also @code{delv1!} and @code{delete1!}.
+@end deffn
+
+@deffn {Scheme Procedure} delv1! item lst
+@deffnx {C Function} scm_delv1_x (item, lst)
+Like @code{delv!}, but only deletes the first occurrence of
+@var{item} from @var{lst}. Tests for equality using
+@code{eqv?}. See also @code{delq1!} and @code{delete1!}.
+@end deffn
+
+@deffn {Scheme Procedure} delete1! item lst
+@deffnx {C Function} scm_delete1_x (item, lst)
+Like @code{delete!}, but only deletes the first occurrence of
+@var{item} from @var{lst}. Tests for equality using
+@code{equal?}. See also @code{delq1!} and @code{delv1!}.
+@end deffn
+
+@deffn {Scheme Procedure} filter pred lst
+@deffnx {Scheme Procedure} filter! pred lst
+Return a list containing all elements from @var{lst} which satisfy the
+predicate @var{pred}. The elements in the result list have the same
+order as in @var{lst}. The order in which @var{pred} is applied to
+the list elements is not specified.
+
+@code{filter!} is allowed, but not required to modify the structure of
+@end deffn
+
+@node List Searching
+@subsubsection List Searching
+
+The following procedures search lists for particular elements. They use
+different comparison predicates for comparing list elements with the
+object to be searched. When they fail, they return @code{#f}, otherwise
+they return the sublist whose car is equal to the search object, where
+equality depends on the equality predicate used.
+
+@rnindex memq
+@deffn {Scheme Procedure} memq x lst
+@deffnx {C Function} scm_memq (x, lst)
+Return the first sublist of @var{lst} whose car is @code{eq?}
+to @var{x} where the sublists of @var{lst} are the non-empty
+lists returned by @code{(list-tail @var{lst} @var{k})} for
+@var{k} less than the length of @var{lst}. If @var{x} does not
+occur in @var{lst}, then @code{#f} (not the empty list) is
+returned.
+@end deffn
+
+@rnindex memv
+@deffn {Scheme Procedure} memv x lst
+@deffnx {C Function} scm_memv (x, lst)
+Return the first sublist of @var{lst} whose car is @code{eqv?}
+to @var{x} where the sublists of @var{lst} are the non-empty
+lists returned by @code{(list-tail @var{lst} @var{k})} for
+@var{k} less than the length of @var{lst}. If @var{x} does not
+occur in @var{lst}, then @code{#f} (not the empty list) is
+returned.
+@end deffn
+
+@rnindex member
+@deffn {Scheme Procedure} member x lst
+@deffnx {C Function} scm_member (x, lst)
+Return the first sublist of @var{lst} whose car is
+@code{equal?} to @var{x} where the sublists of @var{lst} are
+the non-empty lists returned by @code{(list-tail @var{lst}
+@var{k})} for @var{k} less than the length of @var{lst}. If
+@var{x} does not occur in @var{lst}, then @code{#f} (not the
+empty list) is returned.
+@end deffn
+
+
+@node List Mapping
+@subsubsection List Mapping
+
+List processing is very convenient in Scheme because the process of
+iterating over the elements of a list can be highly abstracted. The
+procedures in this section are the most basic iterating procedures for
+lists. They take a procedure and one or more lists as arguments, and
+apply the procedure to each element of the list. They differ in their
+return value.
+
+@rnindex map
+@c begin (texi-doc-string "guile" "map")
+@deffn {Scheme Procedure} map proc arg1 arg2 @dots{}
+@deffnx {Scheme Procedure} map-in-order proc arg1 arg2 @dots{}
+@deffnx {C Function} scm_map (proc, arg1, args)
+Apply @var{proc} to each element of the list @var{arg1} (if only two
+arguments are given), or to the corresponding elements of the argument
+lists (if more than two arguments are given). The result(s) of the
+procedure applications are saved and returned in a list. For
+@code{map}, the order of procedure applications is not specified,
+@code{map-in-order} applies the procedure from left to right to the list
+elements.
+@end deffn
+
+@rnindex for-each
+@c begin (texi-doc-string "guile" "for-each")
+@deffn {Scheme Procedure} for-each proc arg1 arg2 @dots{}
+Like @code{map}, but the procedure is always applied from left to right,
+and the result(s) of the procedure applications are thrown away. The
+return value is not specified.
+@end deffn
+
+
+@node Vectors
+@subsection Vectors
+@tpindex Vectors
+
+Vectors are sequences of Scheme objects. Unlike lists, the length of a
+vector, once the vector is created, cannot be changed. The advantage of
+vectors over lists is that the time required to access one element of a vector
+given its @dfn{position} (synonymous with @dfn{index}), a zero-origin number,
+is constant, whereas lists have an access time linear to the position of the
+accessed element in the list.
+
+Vectors can contain any kind of Scheme object; it is even possible to have
+different types of objects in the same vector. For vectors containing
+vectors, you may wish to use arrays, instead. Note, too, that some array
+procedures operate happily on vectors (@pxref{Arrays}).
+
+@menu
+* Vector Syntax:: Read syntax for vectors.
+* Vector Creation:: Dynamic vector creation and validation.
+* Vector Accessors:: Accessing and modifying vector contents.
+@end menu
+
+
+@node Vector Syntax
+@subsubsection Read Syntax for Vectors
+
+Vectors can literally be entered in source code, just like strings,
+characters or some of the other data types. The read syntax for vectors
+is as follows: A sharp sign (@code{#}), followed by an opening
+parentheses, all elements of the vector in their respective read syntax,
+and finally a closing parentheses. The following are examples of the
+read syntax for vectors; where the first vector only contains numbers
+and the second three different object types: a string, a symbol and a
+number in hexadecimal notation.
+
+@lisp
+#(1 2 3)
+#("Hello" foo #xdeadbeef)
+@end lisp
+
+Like lists, vectors have to be quoted (REFFIXME):
+
+@lisp
+'#(a b c) @result{} #(a b c)
+@end lisp
+
+@node Vector Creation
+@subsubsection Dynamic Vector Creation and Validation
+
+Instead of creating a vector implicitly by using the read syntax just
+described, you can create a vector dynamically by calling one of the
+@code{vector} and @code{list->vector} primitives with the list of Scheme
+values that you want to place into a vector. The size of the vector
+thus created is determined implicitly by the number of arguments given.
+
+@rnindex vector
+@rnindex list->vector
+@deffn {Scheme Procedure} vector . l
+@deffnx {Scheme Procedure} list->vector l
+@deffnx {C Function} scm_vector (l)
+Return a newly allocated vector composed of the
+given arguments. Analogous to @code{list}.
+
+@lisp
+(vector 'a 'b 'c) @result{} #(a b c)
+@end lisp
+@end deffn
+
+(As an aside, an interesting implementation detail is that the Guile
+reader reads the @code{#(@dots{})} syntax by reading everything but the
+initial @code{#} as a @emph{list}, and then passing the list that
+results to @code{list->vector}. Notice how neatly this fits with the
+similarity between the read (and print) syntaxes for lists and vectors.)
+
+The inverse operation is @code{vector->list}:
+
+@rnindex vector->list
+@deffn {Scheme Procedure} vector->list v
+@deffnx {C Function} scm_vector_to_list (v)
+Return a newly allocated list composed of the elements of @var{v}.
+
+@lisp
+(vector->list '#(dah dah didah)) @result{} (dah dah didah)
+(list->vector '(dididit dah)) @result{} #(dididit dah)
+@end lisp
+@end deffn
+
+To allocate a vector with an explicitly specified size, use
+@code{make-vector}. With this primitive you can also specify an initial
+value for the vector elements (the same value for all elements, that
+is):
+
+@rnindex make-vector
+@deffn {Scheme Procedure} make-vector k [fill]
+@deffnx {C Function} scm_make_vector (k, fill)
+Return a newly allocated vector of @var{k} elements. If a
+second argument is given, then each position is initialized to
+@var{fill}. Otherwise the initial contents of each position is
+unspecified.
+@end deffn
+
+To check whether an arbitrary Scheme value @emph{is} a vector, use the
+@code{vector?} primitive:
+
+@rnindex vector?
+@deffn {Scheme Procedure} vector? obj
+@deffnx {C Function} scm_vector_p (obj)
+Return @code{#t} if @var{obj} is a vector, otherwise return
+@code{#f}.
+@end deffn
+
+
+@node Vector Accessors
+@subsubsection Accessing and Modifying Vector Contents
+
+@code{vector-length} and @code{vector-ref} return information about a
+given vector, respectively its size and the elements that are contained
+in the vector.
+
+@rnindex vector-length
+@deffn {Scheme Procedure} vector-length vector
+@deffnx {C Function} scm_vector_length vector
+Return the number of elements in @var{vector} as an exact integer.
+@end deffn
+
+@rnindex vector-ref
+@deffn {Scheme Procedure} vector-ref vector k
+@deffnx {C Function} scm_vector_ref vector k
+Return the contents of position @var{k} of @var{vector}.
+@var{k} must be a valid index of @var{vector}.
+@lisp
+(vector-ref '#(1 1 2 3 5 8 13 21) 5) @result{} 8
+(vector-ref '#(1 1 2 3 5 8 13 21)
+ (let ((i (round (* 2 (acos -1)))))
+ (if (inexact? i)
+ (inexact->exact i)
+ i))) @result{} 13
+@end lisp
+@end deffn
+
+A vector created by one of the dynamic vector constructor procedures
+(@pxref{Vector Creation}) can be modified using the following
+procedures.
+
+@emph{NOTE:} According to R5RS, it is an error to use any of these
+procedures on a literally read vector, because such vectors should be
+considered as constants. Currently, however, Guile does not detect this
+error.
+
+@rnindex vector-set!
+@deffn {Scheme Procedure} vector-set! vector k obj
+@deffnx {C Function} scm_vector_set_x vector k obj
+Store @var{obj} in position @var{k} of @var{vector}.
+@var{k} must be a valid index of @var{vector}.
+The value returned by @samp{vector-set!} is unspecified.
+@lisp
+(let ((vec (vector 0 '(2 2 2 2) "Anna")))
+ (vector-set! vec 1 '("Sue" "Sue"))
+ vec) @result{} #(0 ("Sue" "Sue") "Anna")
+@end lisp
+@end deffn
+
+@rnindex vector-fill!
+@deffn {Scheme Procedure} vector-fill! v fill
+@deffnx {C Function} scm_vector_fill_x (v, fill)
+Store @var{fill} in every position of @var{vector}. The value
+returned by @code{vector-fill!} is unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} vector-move-left! vec1 start1 end1 vec2 start2
+@deffnx {C Function} scm_vector_move_left_x (vec1, start1, end1, vec2, start2)
+Copy elements from @var{vec1}, positions @var{start1} to @var{end1},
+to @var{vec2} starting at position @var{start2}. @var{start1} and
+@var{start2} are inclusive indices; @var{end1} is exclusive.
+
+@code{vector-move-left!} copies elements in leftmost order.
+Therefore, in the case where @var{vec1} and @var{vec2} refer to the
+same vector, @code{vector-move-left!} is usually appropriate when
+@var{start1} is greater than @var{start2}.
+@end deffn
+
+@deffn {Scheme Procedure} vector-move-right! vec1 start1 end1 vec2 start2
+@deffnx {C Function} scm_vector_move_right_x (vec1, start1, end1, vec2, start2)
+Copy elements from @var{vec1}, positions @var{start1} to @var{end1},
+to @var{vec2} starting at position @var{start2}. @var{start1} and
+@var{start2} are inclusive indices; @var{end1} is exclusive.
+
+@code{vector-move-right!} copies elements in rightmost order.
+Therefore, in the case where @var{vec1} and @var{vec2} refer to the
+same vector, @code{vector-move-right!} is usually appropriate when
+@var{start1} is less than @var{start2}.
+@end deffn
+
+
+@node Records
+@subsection Records
+
+A @dfn{record type} is a first class object representing a user-defined
+data type. A @dfn{record} is an instance of a record type.
+
+@deffn {Scheme Procedure} record? obj
+Return @code{#t} if @var{obj} is a record of any type and @code{#f}
+otherwise.
+
+Note that @code{record?} may be true of any Scheme value; there is no
+promise that records are disjoint with other Scheme types.
+@end deffn
+
+@deffn {Scheme Procedure} make-record-type type-name field-names
+Return a @dfn{record-type descriptor}, a value representing a new data
+type disjoint from all others. The @var{type-name} argument must be a
+string, but is only used for debugging purposes (such as the printed
+representation of a record of the new type). The @var{field-names}
+argument is a list of symbols naming the @dfn{fields} of a record of the
+new type. It is an error if the list contains any duplicates. It is
+unspecified how record-type descriptors are represented.
+@end deffn
+
+@deffn {Scheme Procedure} record-constructor rtd [field-names]
+Return a procedure for constructing new members of the type represented
+by @var{rtd}. The returned procedure accepts exactly as many arguments
+as there are symbols in the given list, @var{field-names}; these are
+used, in order, as the initial values of those fields in a new record,
+which is returned by the constructor procedure. The values of any
+fields not named in that list are unspecified. The @var{field-names}
+argument defaults to the list of field names in the call to
+@code{make-record-type} that created the type represented by @var{rtd};
+if the @var{field-names} argument is provided, it is an error if it
+contains any duplicates or any symbols not in the default list.
+@end deffn
+
+@deffn {Scheme Procedure} record-predicate rtd
+Return a procedure for testing membership in the type represented by
+@var{rtd}. The returned procedure accepts exactly one argument and
+returns a true value if the argument is a member of the indicated record
+type; it returns a false value otherwise.
+@end deffn
+
+@deffn {Scheme Procedure} record-accessor rtd field-name
+Return a procedure for reading the value of a particular field of a
+member of the type represented by @var{rtd}. The returned procedure
+accepts exactly one argument which must be a record of the appropriate
+type; it returns the current value of the field named by the symbol
+@var{field-name} in that record. The symbol @var{field-name} must be a
+member of the list of field-names in the call to @code{make-record-type}
+that created the type represented by @var{rtd}.
+@end deffn
+
+@deffn {Scheme Procedure} record-modifier rtd field-name
+Return a procedure for writing the value of a particular field of a
+member of the type represented by @var{rtd}. The returned procedure
+accepts exactly two arguments: first, a record of the appropriate type,
+and second, an arbitrary Scheme value; it modifies the field named by
+the symbol @var{field-name} in that record to contain the given value.
+The returned value of the modifier procedure is unspecified. The symbol
+@var{field-name} must be a member of the list of field-names in the call
+to @code{make-record-type} that created the type represented by
+@var{rtd}.
+@end deffn
+
+@deffn {Scheme Procedure} record-type-descriptor record
+Return a record-type descriptor representing the type of the given
+record. That is, for example, if the returned descriptor were passed to
+@code{record-predicate}, the resulting predicate would return a true
+value when passed the given record. Note that it is not necessarily the
+case that the returned descriptor is the one that was passed to
+@code{record-constructor} in the call that created the constructor
+procedure that created the given record.
+@end deffn
+
+@deffn {Scheme Procedure} record-type-name rtd
+Return the type-name associated with the type represented by rtd. The
+returned value is @code{eqv?} to the @var{type-name} argument given in
+the call to @code{make-record-type} that created the type represented by
+@var{rtd}.
+@end deffn
+
+@deffn {Scheme Procedure} record-type-fields rtd
+Return a list of the symbols naming the fields in members of the type
+represented by @var{rtd}. The returned value is @code{equal?} to the
+field-names argument given in the call to @code{make-record-type} that
+created the type represented by @var{rtd}.
+@end deffn
+
+
+@node Structures
+@subsection Structures
+@tpindex Structures
+
+[FIXME: this is pasted in from Tom Lord's original guile.texi and should
+be reviewed]
+
+A @dfn{structure type} is a first class user-defined data type. A
+@dfn{structure} is an instance of a structure type. A structure type is
+itself a structure.
+
+Structures are less abstract and more general than traditional records.
+In fact, in Guile Scheme, records are implemented using structures.
+
+@menu
+* Structure Concepts:: The structure of Structures
+* Structure Layout:: Defining the layout of structure types
+* Structure Basics:: make-, -ref and -set! procedures for structs
+* Vtables:: Accessing type-specific data
+@end menu
+
+@node Structure Concepts
+@subsubsection Structure Concepts
+
+A structure object consists of a handle, structure data, and a vtable.
+The handle is a Scheme value which points to both the vtable and the
+structure's data. Structure data is a dynamically allocated region of
+memory, private to the structure, divided up into typed fields. A
+vtable is another structure used to hold type-specific data. Multiple
+structures can share a common vtable.
+
+Three concepts are key to understanding structures.
+
+@itemize @bullet{}
+@item @dfn{layout specifications}
+
+Layout specifications determine how memory allocated to structures is
+divided up into fields. Programmers must write a layout specification
+whenever a new type of structure is defined.
+
+@item @dfn{structural accessors}
+
+Structure access is by field number. There is only one set of
+accessors common to all structure objects.
+
+@item @dfn{vtables}
+
+Vtables, themselves structures, are first class representations of
+disjoint sub-types of structures in general. In most cases, when a
+new structure is created, programmers must specify a vtable for the
+new structure. Each vtable has a field describing the layout of its
+instances. Vtables can have additional, user-defined fields as well.
+@end itemize
+
+
+
+@node Structure Layout
+@subsubsection Structure Layout
+
+When a structure is created, a region of memory is allocated to hold its
+state. The @dfn{layout} of the structure's type determines how that
+memory is divided into fields.
+
+Each field has a specified type. There are only three types allowed, each
+corresponding to a one letter code. The allowed types are:
+
+@itemize @bullet{}
+@item 'u' -- unprotected
+
+The field holds binary data that is not GC protected.
+
+@item 'p' -- protected
+
+The field holds a Scheme value and is GC protected.
+
+@item 's' -- self
+
+The field holds a Scheme value and is GC protected. When a structure is
+created with this type of field, the field is initialized to refer to
+the structure's own handle. This kind of field is mainly useful when
+mixing Scheme and C code in which the C code may need to compute a
+structure's handle given only the address of its malloc'd data.
+@end itemize
+
+
+Each field also has an associated access protection. There are only
+three kinds of protection, each corresponding to a one letter code.
+The allowed protections are:
+
+@itemize @bullet{}
+@item 'w' -- writable
+
+The field can be read and written.
+
+@item 'r' -- readable
+
+The field can be read, but not written.
+
+@item 'o' -- opaque
+
+The field can be neither read nor written. This kind
+of protection is for fields useful only to built-in routines.
+@end itemize
+
+A layout specification is described by stringing together pairs
+of letters: one to specify a field type and one to specify a field
+protection. For example, a traditional cons pair type object could
+be described as:
+
+@example
+; cons pairs have two writable fields of Scheme data
+"pwpw"
+@end example
+
+A pair object in which the first field is held constant could be:
+
+@example
+"prpw"
+@end example
+
+Binary fields, (fields of type "u"), hold one @dfn{word} each. The
+size of a word is a machine dependent value defined to be equal to the
+value of the C expression: @code{sizeof (long)}.
+
+The last field of a structure layout may specify a tail array.
+A tail array is indicated by capitalizing the field's protection
+code ('W', 'R' or 'O'). A tail-array field is replaced by
+a read-only binary data field containing an array size. The array
+size is determined at the time the structure is created. It is followed
+by a corresponding number of fields of the type specified for the
+tail array. For example, a conventional Scheme vector can be
+described as:
+
+@example
+; A vector is an arbitrary number of writable fields holding Scheme
+; values:
+"pW"
+@end example
+
+In the above example, field 0 contains the size of the vector and
+fields beginning at 1 contain the vector elements.
+
+A kind of tagged vector (a constant tag followed by conventional
+vector elements) might be:
+
+@example
+"prpW"
+@end example
+
+
+Structure layouts are represented by specially interned symbols whose
+name is a string of type and protection codes. To create a new
+structure layout, use this procedure:
+
+@deffn {Scheme Procedure} make-struct-layout fields
+@deffnx {C Function} scm_make_struct_layout (fields)
+Return a new structure layout object.
+
+@var{fields} must be a string made up of pairs of characters
+strung together. The first character of each pair describes a field
+type, the second a field protection. Allowed types are 'p' for
+GC-protected Scheme data, 'u' for unprotected binary data, and 's' for
+a field that points to the structure itself. Allowed protections
+are 'w' for mutable fields, 'r' for read-only fields, and 'o' for opaque
+fields. The last field protection specification may be capitalized to
+indicate that the field is a tail-array.
+@end deffn
+
+
+
+@node Structure Basics
+@subsubsection Structure Basics
+
+This section describes the basic procedures for creating and accessing
+structures.
+
+@deffn {Scheme Procedure} make-struct vtable tail_array_size . init
+@deffnx {C Function} scm_make_struct (vtable, tail_array_size, init)
+Create a new structure.
+
+@var{type} must be a vtable structure (@pxref{Vtables}).
+
+@var{tail-elts} must be a non-negative integer. If the layout
+specification indicated by @var{type} includes a tail-array,
+this is the number of elements allocated to that array.
+
+The @var{init1}, @dots{} are optional arguments describing how
+successive fields of the structure should be initialized. Only fields
+with protection 'r' or 'w' can be initialized, except for fields of
+type 's', which are automatically initialized to point to the new
+structure itself; fields with protection 'o' can not be initialized by
+Scheme programs.
+
+If fewer optional arguments than initializable fields are supplied,
+fields of type 'p' get default value #f while fields of type 'u' are
+initialized to 0.
+
+Structs are currently the basic representation for record-like data
+structures in Guile. The plan is to eventually replace them with a
+new representation which will at the same time be easier to use and
+more powerful.
+
+For more information, see the documentation for @code{make-vtable-vtable}.
+@end deffn
+
+@deffn {Scheme Procedure} struct? x
+@deffnx {C Function} scm_struct_p (x)
+Return @code{#t} iff @var{x} is a structure object, else
+@code{#f}.
+@end deffn
+
+
+@deffn {Scheme Procedure} struct-ref handle pos
+@deffnx {Scheme Procedure} struct-set! struct n value
+@deffnx {C Function} scm_struct_ref (handle, pos)
+@deffnx {C Function} scm_struct_set_x (struct, n, value)
+Access (or modify) the @var{n}th field of @var{struct}.
+
+If the field is of type 'p', then it can be set to an arbitrary value.
+
+If the field is of type 'u', then it can only be set to a non-negative
+integer value small enough to fit in one machine word.
+@end deffn
+
+
+
+@node Vtables
+@subsubsection Vtables
+
+Vtables are structures that are used to represent structure types. Each
+vtable contains a layout specification in field
+@code{vtable-index-layout} -- instances of the type are laid out
+according to that specification. Vtables contain additional fields
+which are used only internally to libguile. The variable
+@code{vtable-offset-user} is bound to a field number. Vtable fields
+at that position or greater are user definable.
+
+@deffn {Scheme Procedure} struct-vtable handle
+@deffnx {C Function} scm_struct_vtable (handle)
+Return the vtable structure that describes the type of @var{struct}.
+@end deffn
+
+@deffn {Scheme Procedure} struct-vtable? x
+@deffnx {C Function} scm_struct_vtable_p (x)
+Return @code{#t} iff @var{x} is a vtable structure.
+@end deffn
+
+If you have a vtable structure, @code{V}, you can create an instance of
+the type it describes by using @code{(make-struct V ...)}. But where
+does @code{V} itself come from? One possibility is that @code{V} is an
+instance of a user-defined vtable type, @code{V'}, so that @code{V} is
+created by using @code{(make-struct V' ...)}. Another possibility is
+that @code{V} is an instance of the type it itself describes. Vtable
+structures of the second sort are created by this procedure:
+
+@deffn {Scheme Procedure} make-vtable-vtable user_fields tail_array_size . init
+@deffnx {C Function} scm_make_vtable_vtable (user_fields, tail_array_size, init)
+Return a new, self-describing vtable structure.
+
+@var{user-fields} is a string describing user defined fields of the
+vtable beginning at index @code{vtable-offset-user}
+(see @code{make-struct-layout}).
+
+@var{tail-size} specifies the size of the tail-array (if any) of
+this vtable.
+
+@var{init1}, @dots{} are the optional initializers for the fields of
+the vtable.
+
+Vtables have one initializable system field---the struct printer.
+This field comes before the user fields in the initializers passed
+to @code{make-vtable-vtable} and @code{make-struct}, and thus works as
+a third optional argument to @code{make-vtable-vtable} and a fourth to
+@code{make-struct} when creating vtables:
+
+If the value is a procedure, it will be called instead of the standard
+printer whenever a struct described by this vtable is printed.
+The procedure will be called with arguments STRUCT and PORT.
+
+The structure of a struct is described by a vtable, so the vtable is
+in essence the type of the struct. The vtable is itself a struct with
+a vtable. This could go on forever if it weren't for the
+vtable-vtables which are self-describing vtables, and thus terminate
+the chain.
+
+There are several potential ways of using structs, but the standard
+one is to use three kinds of structs, together building up a type
+sub-system: one vtable-vtable working as the root and one or several
+"types", each with a set of "instances". (The vtable-vtable should be
+compared to the class <class> which is the class of itself.)
+
+@lisp
+(define ball-root (make-vtable-vtable "pr" 0))
+
+(define (make-ball-type ball-color)
+ (make-struct ball-root 0
+ (make-struct-layout "pw")
+ (lambda (ball port)
+ (format port "#<a ~A ball owned by ~A>"
+ (color ball)
+ (owner ball)))
+ ball-color))
+(define (color ball) (struct-ref (struct-vtable ball) vtable-offset-user))
+(define (owner ball) (struct-ref ball 0))
+
+(define red (make-ball-type 'red))
+(define green (make-ball-type 'green))
+
+(define (make-ball type owner) (make-struct type 0 owner))
+
+(define ball (make-ball green 'Nisse))
+ball @result{} #<a green ball owned by Nisse>
+@end lisp
+@end deffn
+
+@deffn {Scheme Procedure} struct-vtable-name vtable
+@deffnx {C Function} scm_struct_vtable_name (vtable)
+Return the name of the vtable @var{vtable}.
+@end deffn
+
+@deffn {Scheme Procedure} set-struct-vtable-name! vtable name
+@deffnx {C Function} scm_set_struct_vtable_name_x (vtable, name)
+Set the name of the vtable @var{vtable} to @var{name}.
+@end deffn
+
+@deffn {Scheme Procedure} struct-vtable-tag handle
+@deffnx {C Function} scm_struct_vtable_tag (handle)
+Return the vtable tag of the structure @var{handle}.
+@end deffn
+
+
+@node Arrays
+@subsection Arrays
+@tpindex Arrays
+
+@menu
+* Conventional Arrays:: Arrays with arbitrary data.
+* Array Mapping:: Applying a procedure to the contents of an array.
+* Uniform Arrays:: Arrays with data of a single type.
+* Bit Vectors:: Vectors of bits.
+@end menu
+
+@node Conventional Arrays
+@subsubsection Conventional Arrays
+
+@dfn{Conventional arrays} are a collection of cells organized into an
+arbitrary number of dimensions. Each cell can hold any kind of Scheme
+value and can be accessed in constant time by supplying an index for
+each dimension.
+
+This contrasts with uniform arrays, which use memory more efficiently
+but can hold data of only a single type. It contrasts also with lists
+where inserting and deleting cells is more efficient, but more time is
+usually required to access a particular cell.
+
+A conventional array is displayed as @code{#} followed by the @dfn{rank}
+(number of dimensions) followed by the cells, organized into dimensions
+using parentheses. The nesting depth of the parentheses is equal to
+the rank.
+
+When an array is created, the range of each dimension must be
+specified, e.g., to create a 2@cross{}3 array with a zero-based index:
+
+@example
+(make-array 'ho 2 3) @result{} #2((ho ho ho) (ho ho ho))
+@end example
+
+The range of each dimension can also be given explicitly, e.g., another
+way to create the same array:
+
+@example
+(make-array 'ho '(0 1) '(0 2)) @result{} #2((ho ho ho) (ho ho ho))
+@end example
+
+A conventional array with one dimension based at zero is identical to
+a vector:
+
+@example
+(make-array 'ho 3) @result{} #(ho ho ho)
+@end example
+
+The following procedures can be used with conventional arrays (or
+vectors). An argument shown as @var{idx}@dots{} means one parameter
+for each dimension in the array. Or a @var{idxlist} is a list of such
+values, one for each dimension.
+
+@deffn {Scheme Procedure} array? obj [prot]
+@deffnx {C Function} scm_array_p (obj, prot)
+Return @code{#t} if the @var{obj} is an array, and @code{#f} if
+not.
+
+The @var{prot} argument is used with uniform arrays (@pxref{Uniform
+Arrays}). If given then the return is @code{#t} if @var{obj} is an
+array and of that prototype.
+@end deffn
+
+@deffn {Scheme Procedure} make-array initial-value bound @dots{}
+Create and return an array that has as many dimensions as there are
+@var{bound}s and fill it with @var{initial-value}.
+
+Each @var{bound}
+may be a positive non-zero integer @var{N}, in which case the index for
+that dimension can range from 0 through @var{N-1}; or an explicit index
+range specifier in the form @code{(LOWER UPPER)}, where both @var{lower}
+and @var{upper} are integers, possibly less than zero, and possibly the
+same number (however, @var{lower} cannot be greater than @var{upper}).
+See examples above.
+@end deffn
+
+@c array-ref's type is `compiled-closure'. There's some weird stuff
+@c going on in array.c, too. Let's call it a primitive. -twp
+
+@deffn {Scheme Procedure} array-ref array idx @dots{}
+@deffnx {Scheme Procedure} uniform-vector-ref vec args
+@deffnx {C Function} scm_uniform_vector_ref (vec, args)
+Return the element at @code{(idx @dots{})} in @var{array}.
+
+@example
+(define a (make-array 999 '(1 2) '(3 4)))
+(array-ref a 2 4) @result{} 999
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} array-in-bounds? array idx @dots{}
+@deffnx {C Function} scm_array_in_bounds_p (array, idxlist)
+Return @code{#t} if the given index would be acceptable to
+@code{array-ref}.
+
+@example
+(define a (make-array #f '(1 2) '(3 4)))
+(array-in-bounds? a 2 3) @result{} #f
+(array-in-bounds? a 0 0) @result{} #f
+@end example
+@end deffn
+
+@c fixme: why do these sigs differ? -ttn 2001/07/19 01:14:12
+@deffn {Scheme Procedure} array-set! array obj idx @dots{}
+@deffnx {Scheme Procedure} uniform-array-set1! array obj idxlist
+@deffnx {C Function} scm_array_set_x (array, obj, idxlist)
+Set the element at @code{(idx @dots{})} in @var{array} to @var{obj}.
+The return value is unspecified.
+
+@example
+(define a (make-array #f '(0 1) '(0 1)))
+(array-set! a #t 1 1)
+a @result{} #2((#f #f) (#f #t))
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} make-shared-array oldarray mapfunc bound @dots{}
+@deffnx {C Function} scm_make_shared_array (oldarray, mapfunc, boundlist)
+@code{make-shared-array} can be used to create shared subarrays of other
+arrays. The @var{mapper} is a function that translates coordinates in
+the new array into coordinates in the old array. A @var{mapper} must be
+linear, and its range must stay within the bounds of the old array, but
+it can be otherwise arbitrary. A simple example:
+
+@lisp
+(define fred (make-array #f 8 8))
+(define freds-diagonal
+ (make-shared-array fred (lambda (i) (list i i)) 8))
+(array-set! freds-diagonal 'foo 3)
+(array-ref fred 3 3) @result{} foo
+(define freds-center
+ (make-shared-array fred (lambda (i j) (list (+ 3 i) (+ 3 j))) 2 2))
+(array-ref freds-center 0 0) @result{} foo
+@end lisp
+@end deffn
+
+@deffn {Scheme Procedure} shared-array-increments array
+@deffnx {C Function} scm_shared_array_increments (array)
+For each dimension, return the distance between elements in the root vector.
+@end deffn
+
+@deffn {Scheme Procedure} shared-array-offset array
+@deffnx {C Function} scm_shared_array_offset (array)
+Return the root vector index of the first element in the array.
+@end deffn
+
+@deffn {Scheme Procedure} shared-array-root array
+@deffnx {C Function} scm_shared_array_root (array)
+Return the root vector of a shared array.
+@end deffn
+
+@deffn {Scheme Procedure} transpose-array array dim1 @dots{}
+@deffnx {C Function} scm_transpose_array (array, dimlist)
+Return an array sharing contents with @var{array}, but with
+dimensions arranged in a different order. There must be one
+@var{dim} argument for each dimension of @var{array}.
+@var{dim1}, @var{dim2}, @dots{} should be integers between 0
+and the rank of the array to be returned. Each integer in that
+range must appear at least once in the argument list.
+
+The values of @var{dim1}, @var{dim2}, @dots{} correspond to
+dimensions in the array to be returned, and their positions in the
+argument list to dimensions of @var{array}. Several @var{dim}s
+may have the same value, in which case the returned array will
+have smaller rank than @var{array}.
+
+@lisp
+(transpose-array '#2((a b) (c d)) 1 0) @result{} #2((a c) (b d))
+(transpose-array '#2((a b) (c d)) 0 0) @result{} #1(a d)
+(transpose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1 1 0) @result{}
+ #2((a 4) (b 5) (c 6))
+@end lisp
+@end deffn
+
+@deffn {Scheme Procedure} enclose-array array dim1 @dots{}
+@deffnx {C Function} scm_enclose_array (array, dimlist)
+@var{dim1}, @var{dim2} @dots{} should be nonnegative integers less than
+the rank of @var{array}. @code{enclose-array} returns an array
+resembling an array of shared arrays. The dimensions of each shared
+array are the same as the @var{dim}th dimensions of the original array,
+the dimensions of the outer array are the same as those of the original
+array that did not match a @var{dim}.
+
+An enclosed array is not a general Scheme array. Its elements may not
+be set using @code{array-set!}. Two references to the same element of
+an enclosed array will be @code{equal?} but will not in general be
+@code{eq?}. The value returned by @code{array-prototype} when given an
+enclosed array is unspecified.
+
+For example,
+
+@lisp
+(enclose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1)
+@result{}
+#<enclosed-array (#1(a d) #1(b e) #1(c f)) (#1(1 4) #1(2 5) #1(3 6))>
+
+(enclose-array '#3(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1 0)
+@result{}
+#<enclosed-array #2((a 1) (d 4)) #2((b 2) (e 5)) #2((c 3) (f 6))>
+@end lisp
+@end deffn
+
+@deffn {Scheme Procedure} array-shape array
+@deffnx {Scheme Procedure} array-dimensions array
+@deffnx {C Function} scm_array_dimensions (array)
+Return a list of the bounds for each dimenson of @var{array}.
+
+@code{array-shape} gives @code{(@var{lower} @var{upper})} for each
+dimension. @code{array-dimensions} instead returns just
+@math{@var{upper}+1} for dimensions with a 0 lower bound. Both are
+suitable as input to @code{make-array}.
+
+For example,
+
+@example
+(define a (make-array 'foo '(-1 3) 5))
+(array-shape a) @result{} ((-1 3) (0 4))
+(array-dimensions a) @result{} ((-1 3) 5)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} array-rank obj
+@deffnx {C Function} scm_array_rank (obj)
+Return the number of dimensions of an array @var{obj}, or if @var{obj}
+is not an array then return 0.
+@end deffn
+
+@deffn {Scheme Procedure} array->list array
+@deffnx {C Function} scm_array_to_list (array)
+Return a list consisting of all the elements, in order, of
+@var{array}.
+@end deffn
+
+@c FIXME: Describe how the order affects the copying (it matters for
+@c shared arrays with the same underlying root vector, presumably).
+@c
+@deffn {Scheme Procedure} array-copy! src dst
+@deffnx {Scheme Procedure} array-copy-in-order! src dst
+@deffnx {C Function} scm_array_copy_x (src, dst)
+Copy every element from vector or array @var{src} to the corresponding
+element of @var{dst}. @var{dst} must have the same rank as @var{src},
+and be at least as large in each dimension. The return value is
+unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} array-fill! array fill
+@deffnx {C Function} scm_array_fill_x (array, fill)
+Store @var{fill} in every element of @var{array}. The value returned
+is unspecified.
+@end deffn
+
+@c begin (texi-doc-string "guile" "array-equal?")
+@deffn {Scheme Procedure} array-equal? array1 array2 @dots{}
+Return @code{#t} if all arguments are arrays with the same shape, the
+same type, and have corresponding elements which are either
+@code{equal?} or @code{array-equal?}. This function differs from
+@code{equal?} in that a one dimensional shared array may be
+@var{array-equal?} but not @var{equal?} to a vector or uniform vector.
+@end deffn
+
+@deffn {Scheme Procedure} array-contents array [strict]
+@deffnx {C Function} scm_array_contents (array, strict)
+If @var{array} may be @dfn{unrolled} into a one dimensional shared array
+without changing their order (last subscript changing fastest), then
+@code{array-contents} returns that shared array, otherwise it returns
+@code{#f}. All arrays made by @code{make-array} and
+@code{make-uniform-array} may be unrolled, some arrays made by
+@code{make-shared-array} may not be.
+
+If the optional argument @var{strict} is provided, a shared array will
+be returned only if its elements are stored internally contiguous in
+memory.
+@end deffn
+
+@node Array Mapping
+@subsubsection Array Mapping
+
+@c FIXME: array-map! accepts no source arrays at all, and in that
+@c case makes calls "(proc)". Is that meant to be a documented
+@c feature?
+@c
+@c FIXME: array-for-each doesn't say what happens if the sources have
+@c different index ranges. The code currently iterates over the
+@c indices of the first and expects the others to cover those. That
+@c at least vaguely matches array-map!, but is is meant to be a
+@c documented feature?
+
+@deffn {Scheme Procedure} array-map! dst proc src1 @dots{} srcN
+@deffnx {Scheme Procedure} array-map-in-order! dst proc src1 @dots{} srcN
+@deffnx {C Function} scm_array_map_x (dst, proc, srclist)
+Set each element of the @var{dst} array to values obtained from calls
+to @var{proc}. The value returned is unspecified.
+
+Each call is @code{(@var{proc} @var{elem1} @dots{} @var{elemN})},
+where each @var{elem} is from the corresponding @var{src} array, at
+the @var{dst} index. @code{array-map-in-order!} makes the calls in
+row-major order, @code{array-map!} makes them in an unspecified order.
+
+The @var{src} arrays must have the same number of dimensions as
+@var{dst}, and must have a range for each dimension which covers the
+range in @var{dst}. This ensures all @var{dst} indices are valid in
+each @var{src}.
+@end deffn
+
+@deffn {Scheme Procedure} array-for-each proc src1 @dots{} srcN
+@deffnx {C Function} scm_array_for_each (proc, src1, srclist)
+Apply @var{proc} to each tuple of elements of @var{src1} @dots{}
+@var{srcN}, in row-major order. The value returned is unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} array-index-map! dst proc
+@deffnx {C Function} scm_array_index_map_x (dst, proc)
+Set each element of the @var{dst} array to values returned by calls to
+@var{proc}. The value returned is unspecified.
+
+Each call is @code{(@var{proc} @var{i1} @dots{} @var{iN})}, where
+@var{i1}@dots{}@var{iN} is the destination index, one parameter for
+each dimension. The order in which the calls are made is unspecified.
+
+For example, to create a @m{4\times4, 4x4} matrix representing a
+cyclic group,
+
+@tex
+\advance\leftskip by 2\lispnarrowing {
+$\left(\matrix{%
+0 & 1 & 2 & 3 \cr
+1 & 2 & 3 & 0 \cr
+2 & 3 & 0 & 1 \cr
+3 & 0 & 1 & 2 \cr
+}\right)$} \par
+@end tex
+@ifnottex
+@example
+ / 0 1 2 3 \
+ | 1 2 3 0 |
+ | 2 3 0 1 |
+ \ 3 0 1 2 /
+@end example
+@end ifnottex
+
+@example
+(define a (make-array #f 4 4))
+(array-index-map! a (lambda (i j)
+ (modulo (+ i j) 4)))
+@end example
+@end deffn
+
+@node Uniform Arrays
+@subsubsection Uniform Arrays
+@tpindex Uniform Arrays
+
+@noindent
+@dfn{Uniform arrays} have elements all of the
+same type and occupy less storage than conventional
+arrays. Uniform arrays with a single zero-based dimension
+are also known as @dfn{uniform vectors}. The procedures in
+this section can also be used on conventional arrays, vectors,
+bit-vectors and strings.
+
+@noindent
+When creating a uniform array, the type of data to be stored
+is indicated with a @var{prototype} argument. The following table
+lists the types available and example prototypes:
+
+@example
+prototype type printing character
+
+#t boolean (bit-vector) b
+#\a char (string) a
+#\nul byte (integer) y
+'s short (integer) h
+1 unsigned long (integer) u
+-1 signed long (integer) e
+'l signed long long (integer) l
+1.0 float (single precision) s
+1/3 double (double precision float) i
+0+i complex (double precision) c
+() conventional vector
+@end example
+
+Note that with the introduction of exact fractions in Guile 1.8,
+@samp{1/3} here is now a fraction, where previously such an expression
+was a double @samp{0.333@dots{}}. For most normal usages this should
+be source code compatible.
+
+Unshared uniform arrays of characters with a single zero-based dimension
+are identical to strings:
+
+@example
+(make-uniform-array #\a 3) @result{}
+"aaa"
+@end example
+
+@noindent
+Unshared uniform arrays of booleans with a single zero-based dimension
+are identical to @ref{Bit Vectors, bit-vectors}.
+
+@example
+(make-uniform-array #t 3) @result{}
+#*111
+@end example
+
+@noindent
+Other uniform vectors are written in a form similar to that of vectors,
+except that a single character from the above table is put between
+@code{#} and @code{(}. For example, a uniform vector of signed
+long integers is displayed in the form @code{'#e(3 5 9)}.
+
+@deffn {Scheme Procedure} make-uniform-array prototype bound1 bound2 @dots{}
+Create and return a uniform array of type corresponding to
+@var{prototype} that has as many dimensions as there are @var{bound}s
+and fill it with @var{prototype}.
+@end deffn
+
+@deffn {Scheme Procedure} array-prototype ra
+@deffnx {C Function} scm_array_prototype (ra)
+Return an object that would produce an array of the same type
+as @var{array}, if used as the @var{prototype} for
+@code{make-uniform-array}.
+@end deffn
+
+@deffn {Scheme Procedure} list->uniform-array ndim prot lst
+@deffnx {Scheme Procedure} list->uniform-vector prot lst
+@deffnx {C Function} scm_list_to_uniform_array (ndim, prot, lst)
+Return a uniform array of the type indicated by prototype
+@var{prot} with elements the same as those of @var{lst}.
+Elements must be of the appropriate type, no coercions are
+done.
+@end deffn
+
+@deffn {Scheme Procedure} uniform-vector-fill! uve fill
+Store @var{fill} in every element of @var{uve}. The value returned is
+unspecified.
+@end deffn
+
+@deffn {Scheme Procedure} uniform-vector-length v
+@deffnx {C Function} scm_uniform_vector_length (v)
+Return the number of elements in @var{uve}.
+@end deffn
+
+@deffn {Scheme Procedure} dimensions->uniform-array dims prot [fill]
+@deffnx {Scheme Procedure} make-uniform-vector length prototype [fill]
+@deffnx {C Function} scm_dimensions_to_uniform_array (dims, prot, fill)
+Create and return a uniform array or vector of type
+corresponding to @var{prototype} with dimensions @var{dims} or
+length @var{length}. If @var{fill} is supplied, it's used to
+fill the array, otherwise @var{prototype} is used.
+@end deffn
+
+@c Another compiled-closure. -twp
+
+@deffn {Scheme Procedure} uniform-array-read! ra [port_or_fd [start [end]]]
+@deffnx {Scheme Procedure} uniform-vector-read! uve [port-or-fdes] [start] [end]
+@deffnx {C Function} scm_uniform_array_read_x (ra, port_or_fd, start, end)
+Attempt to read all elements of @var{ura}, in lexicographic order, as
+binary objects from @var{port-or-fdes}.
+If an end of file is encountered,
+the objects up to that point are put into @var{ura}
+(starting at the beginning) and the remainder of the array is
+unchanged.
+
+The optional arguments @var{start} and @var{end} allow
+a specified region of a vector (or linearized array) to be read,
+leaving the remainder of the vector unchanged.
+
+@code{uniform-array-read!} returns the number of objects read.
+@var{port-or-fdes} may be omitted, in which case it defaults to the value
+returned by @code{(current-input-port)}.
+@end deffn
+
+@deffn {Scheme Procedure} uniform-array-write v [port_or_fd [start [end]]]
+@deffnx {Scheme Procedure} uniform-vector-write uve [port-or-fdes] [start] [end]
+@deffnx {C Function} scm_uniform_array_write (v, port_or_fd, start, end)
+Writes all elements of @var{ura} as binary objects to
+@var{port-or-fdes}.
+
+The optional arguments @var{start}
+and @var{end} allow
+a specified region of a vector (or linearized array) to be written.
+
+The number of objects actually written is returned.
+@var{port-or-fdes} may be
+omitted, in which case it defaults to the value returned by
+@code{(current-output-port)}.
+@end deffn
+
+@node Bit Vectors
+@subsubsection Bit Vectors
+
+@noindent
+Bit vectors are a specific type of uniform array: an array of booleans
+with a single zero-based index.
+
+@noindent
+They are displayed as a sequence of @code{0}s and
+@code{1}s prefixed by @code{#*}, e.g.,
+
+@example
+(make-uniform-vector 8 #t #f) @result{}
+#*00000000
+@end example
+
+@deffn {Scheme Procedure} bit-count bool bitvector
+@deffnx {C Function} scm_bit_count (bool, bitvector)
+Return a count of how many entries in @var{bitvector} are equal to
+@var{bool}. For example,
+
+@example
+(bit-count #f #*000111000) @result{} 6
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} bit-position bool bitvector start
+@deffnx {C Function} scm_bit_position (bool, bitvector, start)
+Return the index of the first occurrance of @var{bool} in
+@var{bitvector}, starting from @var{start}. If there is no @var{bool}
+entry between @var{start} and the end of @var{bitvector}, then return
+@code{#f}. For example,
+
+@example
+(bit-position #t #*000101 0) @result{} 3
+(bit-position #f #*0001111 3) @result{} #f
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} bit-invert! bitvector
+@deffnx {C Function} scm_bit_invert_x (bitvector)
+Modify @var{bitvector} by replacing each element with its negation.
+@end deffn
+
+@deffn {Scheme Procedure} bit-set*! bitvector uvec bool
+@deffnx {C Function} scm_bit_set_star_x (bitvector, uvec, bool)
+Set entries of @var{bitvector} to @var{bool}, with @var{uvec}
+selecting the entries to change. The return value is unspecified.
+
+If @var{uvec} is a bit vector, then those entries where it has
+@code{#t} are the ones in @var{bitvector} which are set to @var{bool}.
+@var{uvec} and @var{bitvector} must be the same length. When
+@var{bool} is @code{#t} it's like @var{uvec} is OR'ed into
+@var{bitvector}. Or when @var{bool} is @code{#f} it can be seen as an
+ANDNOT.
+
+@example
+(define bv #*01000010)
+(bit-set*! bv #*10010001 #t)
+bv
+@result{} #*11010011
+@end example
+
+If @var{uvec} is a uniform vector of unsigned long integers, then
+they're indexes into @var{bitvector} which are set to @var{bool}.
+
+@example
+(define bv #*01000010)
+(bit-set*! bv #u(5 2 7) #t)
+bv
+@result{} #*01100111
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} bit-count* bitvector uvec bool
+@deffnx {C Function} scm_bit_count_star (bitvector, uvec, bool)
+Return a count of how many entries in @var{bitvector} are equal to
+@var{bool}, with @var{uvec} selecting the entries to consider.
+
+@var{uvec} is interpreted in the same way as for @code{bit-set*!}
+above. Namely, if @var{uvec} is a bit vector then entries which have
+@code{#t} there are considered in @var{bitvector}. Or if @var{uvec}
+is a uniform vector of unsigned long integers then it's the indexes in
+@var{bitvector} to consider.
+
+For example,
+
+@example
+(bit-count* #*01110111 #*11001101 #t) @result{} 3
+(bit-count* #*01110111 #u(7 0 4) #f) @result{} 2
+@end example
+@end deffn
+
+
+@node Dictionary Types
+@subsection Dictionary Types
+
+A @dfn{dictionary} object is a data structure used to index
+information in a user-defined way. In standard Scheme, the main
+aggregate data types are lists and vectors. Lists are not really
+indexed at all, and vectors are indexed only by number
+(e.g. @code{(vector-ref foo 5)}). Often you will find it useful
+to index your data on some other type; for example, in a library
+catalog you might want to look up a book by the name of its
+author. Dictionaries are used to help you organize information in
+such a way.
+
+An @dfn{association list} (or @dfn{alist} for short) is a list of
+key-value pairs. Each pair represents a single quantity or
+object; the @code{car} of the pair is a key which is used to
+identify the object, and the @code{cdr} is the object's value.
+
+A @dfn{hash table} also permits you to index objects with
+arbitrary keys, but in a way that makes looking up any one object
+extremely fast. A well-designed hash system makes hash table
+lookups almost as fast as conventional array or vector references.
+
+Alists are popular among Lisp programmers because they use only
+the language's primitive operations (lists, @dfn{car}, @dfn{cdr}
+and the equality primitives). No changes to the language core are
+necessary. Therefore, with Scheme's built-in list manipulation
+facilities, it is very convenient to handle data stored in an
+association list. Also, alists are highly portable and can be
+easily implemented on even the most minimal Lisp systems.
+
+However, alists are inefficient, especially for storing large
+quantities of data. Because we want Guile to be useful for large
+software systems as well as small ones, Guile provides a rich set
+of tools for using either association lists or hash tables.
+
+@node Association Lists
+@subsection Association Lists
+@tpindex Association Lists
+@tpindex Alist
+
+@cindex Association List
+@cindex Alist
+@cindex Database
+
+An association list is a conventional data structure that is often used
+to implement simple key-value databases. It consists of a list of
+entries in which each entry is a pair. The @dfn{key} of each entry is
+the @code{car} of the pair and the @dfn{value} of each entry is the
+@code{cdr}.
+
+@example
+ASSOCIATION LIST ::= '( (KEY1 . VALUE1)
+ (KEY2 . VALUE2)
+ (KEY3 . VALUE3)
+ @dots{}
+ )
+@end example
+
+@noindent
+Association lists are also known, for short, as @dfn{alists}.
+
+The structure of an association list is just one example of the infinite
+number of possible structures that can be built using pairs and lists.
+As such, the keys and values in an association list can be manipulated
+using the general list structure procedures @code{cons}, @code{car},
+@code{cdr}, @code{set-car!}, @code{set-cdr!} and so on. However,
+because association lists are so useful, Guile also provides specific
+procedures for manipulating them.
+
+@menu
+* Alist Key Equality::
+* Adding or Setting Alist Entries::
+* Retrieving Alist Entries::
+* Removing Alist Entries::
+* Sloppy Alist Functions::
+* Alist Example::
+@end menu
+
+@node Alist Key Equality
+@subsubsection Alist Key Equality
+
+All of Guile's dedicated association list procedures, apart from
+@code{acons}, come in three flavours, depending on the level of equality
+that is required to decide whether an existing key in the association
+list is the same as the key that the procedure call uses to identify the
+required entry.
+
+@itemize @bullet
+@item
+Procedures with @dfn{assq} in their name use @code{eq?} to determine key
+equality.
+
+@item
+Procedures with @dfn{assv} in their name use @code{eqv?} to determine
+key equality.
+
+@item
+Procedures with @dfn{assoc} in their name use @code{equal?} to
+determine key equality.
+@end itemize
+
+@code{acons} is an exception because it is used to build association
+lists which do not require their entries' keys to be unique.
+
+@node Adding or Setting Alist Entries
+@subsubsection Adding or Setting Alist Entries
+
+@code{acons} adds a new entry to an association list and returns the
+combined association list. The combined alist is formed by consing the
+new entry onto the head of the alist specified in the @code{acons}
+procedure call. So the specified alist is not modified, but its
+contents become shared with the tail of the combined alist that
+@code{acons} returns.
+
+In the most common usage of @code{acons}, a variable holding the
+original association list is updated with the combined alist:
+
+@example
+(set! address-list (acons name address address-list))
+@end example
+
+In such cases, it doesn't matter that the old and new values of
+@code{address-list} share some of their contents, since the old value is
+usually no longer independently accessible.
+
+Note that @code{acons} adds the specified new entry regardless of
+whether the alist may already contain entries with keys that are, in
+some sense, the same as that of the new entry. Thus @code{acons} is
+ideal for building alists where there is no concept of key uniqueness.
+
+@example
+(set! task-list (acons 3 "pay gas bill" '()))
+task-list
+@result{}
+((3 . "pay gas bill"))
+
+(set! task-list (acons 3 "tidy bedroom" task-list))
+task-list
+@result{}
+((3 . "tidy bedroom") (3 . "pay gas bill"))
+@end example
+
+@code{assq-set!}, @code{assv-set!} and @code{assoc-set!} are used to add
+or replace an entry in an association list where there @emph{is} a
+concept of key uniqueness. If the specified association list already
+contains an entry whose key is the same as that specified in the
+procedure call, the existing entry is replaced by the new one.
+Otherwise, the new entry is consed onto the head of the old association
+list to create the combined alist. In all cases, these procedures
+return the combined alist.
+
+@code{assq-set!} and friends @emph{may} destructively modify the
+structure of the old association list in such a way that an existing
+variable is correctly updated without having to @code{set!} it to the
+value returned:
+
+@example
+address-list
+@result{}
+(("mary" . "34 Elm Road") ("james" . "16 Bow Street"))
+
+(assoc-set! address-list "james" "1a London Road")
+@result{}
+(("mary" . "34 Elm Road") ("james" . "1a London Road"))
+
+address-list
+@result{}
+(("mary" . "34 Elm Road") ("james" . "1a London Road"))
+@end example
+
+Or they may not:
+
+@example
+(assoc-set! address-list "bob" "11 Newington Avenue")
+@result{}
+(("bob" . "11 Newington Avenue") ("mary" . "34 Elm Road")
+ ("james" . "1a London Road"))
+
+address-list
+@result{}
+(("mary" . "34 Elm Road") ("james" . "1a London Road"))
+@end example
+
+The only safe way to update an association list variable when adding or
+replacing an entry like this is to @code{set!} the variable to the
+returned value:
+
+@example
+(set! address-list
+ (assoc-set! address-list "bob" "11 Newington Avenue"))
+address-list
+@result{}
+(("bob" . "11 Newington Avenue") ("mary" . "34 Elm Road")
+ ("james" . "1a London Road"))
+@end example
+
+Because of this slight inconvenience, you may find it more convenient to
+use hash tables to store dictionary data. If your application will not
+be modifying the contents of an alist very often, this may not make much
+difference to you.
+
+If you need to keep the old value of an association list in a form
+independent from the list that results from modification by
+@code{acons}, @code{assq-set!}, @code{assv-set!} or @code{assoc-set!},
+use @code{list-copy} to copy the old association list before modifying
+it.
+
+@deffn {Scheme Procedure} acons key value alist
+@deffnx {C Function} scm_acons (key, value, alist)
+Add a new key-value pair to @var{alist}. A new pair is
+created whose car is @var{key} and whose cdr is @var{value}, and the
+pair is consed onto @var{alist}, and the new list is returned. This
+function is @emph{not} destructive; @var{alist} is not modified.
+@end deffn
+
+@deffn {Scheme Procedure} assq-set! alist key val
+@deffnx {Scheme Procedure} assv-set! alist key value
+@deffnx {Scheme Procedure} assoc-set! alist key value
+@deffnx {C Function} scm_assq_set_x (alist, key, val)
+@deffnx {C Function} scm_assv_set_x (alist, key, val)
+@deffnx {C Function} scm_assoc_set_x (alist, key, val)
+Reassociate @var{key} in @var{alist} with @var{value}: find any existing
+@var{alist} entry for @var{key} and associate it with the new
+@var{value}. If @var{alist} does not contain an entry for @var{key},
+add a new one. Return the (possibly new) alist.
+
+These functions do not attempt to verify the structure of @var{alist},
+and so may cause unusual results if passed an object that is not an
+association list.
+@end deffn
+
+@node Retrieving Alist Entries
+@subsubsection Retrieving Alist Entries
+@rnindex assq
+@rnindex assv
+@rnindex assoc
+
+@code{assq}, @code{assv} and @code{assoc} take an alist and a key as
+arguments and return the entry for that key if an entry exists, or
+@code{#f} if there is no entry for that key. Note that, in the cases
+where an entry exists, these procedures return the complete entry, that
+is @code{(KEY . VALUE)}, not just the value.
+
+@deffn {Scheme Procedure} assq key alist
+@deffnx {Scheme Procedure} assv key alist
+@deffnx {Scheme Procedure} assoc key alist
+@deffnx {C Function} scm_assq (key, alist)
+@deffnx {C Function} scm_assv (key, alist)
+@deffnx {C Function} scm_assoc (key, alist)
+Fetch the entry in @var{alist} that is associated with @var{key}. To
+decide whether the argument @var{key} matches a particular entry in
+@var{alist}, @code{assq} compares keys with @code{eq?}, @code{assv}
+uses @code{eqv?} and @code{assoc} uses @code{equal?}. If @var{key}
+cannot be found in @var{alist} (according to whichever equality
+predicate is in use), then return @code{#f}. These functions
+return the entire alist entry found (i.e. both the key and the value).
+@end deffn
+
+@code{assq-ref}, @code{assv-ref} and @code{assoc-ref}, on the other
+hand, take an alist and a key and return @emph{just the value} for that
+key, if an entry exists. If there is no entry for the specified key,
+these procedures return @code{#f}.
+
+This creates an ambiguity: if the return value is @code{#f}, it means
+either that there is no entry with the specified key, or that there
+@emph{is} an entry for the specified key, with value @code{#f}.
+Consequently, @code{assq-ref} and friends should only be used where it
+is known that an entry exists, or where the ambiguity doesn't matter
+for some other reason.
+
+@deffn {Scheme Procedure} assq-ref alist key
+@deffnx {Scheme Procedure} assv-ref alist key
+@deffnx {Scheme Procedure} assoc-ref alist key
+@deffnx {C Function} scm_assq_ref (alist, key)
+@deffnx {C Function} scm_assv_ref (alist, key)
+@deffnx {C Function} scm_assoc_ref (alist, key)
+Like @code{assq}, @code{assv} and @code{assoc}, except that only the
+value associated with @var{key} in @var{alist} is returned. These
+functions are equivalent to
+
+@lisp
+(let ((ent (@var{associator} @var{key} @var{alist})))
+ (and ent (cdr ent)))
+@end lisp
+
+where @var{associator} is one of @code{assq}, @code{assv} or @code{assoc}.
+@end deffn
+
+@node Removing Alist Entries
+@subsubsection Removing Alist Entries
+
+To remove the element from an association list whose key matches a
+specified key, use @code{assq-remove!}, @code{assv-remove!} or
+@code{assoc-remove!} (depending, as usual, on the level of equality
+required between the key that you specify and the keys in the
+association list).
+
+As with @code{assq-set!} and friends, the specified alist may or may not
+be modified destructively, and the only safe way to update a variable
+containing the alist is to @code{set!} it to the value that
+@code{assq-remove!} and friends return.
+
+@example
+address-list
+@result{}
+(("bob" . "11 Newington Avenue") ("mary" . "34 Elm Road")
+ ("james" . "1a London Road"))
+
+(set! address-list (assoc-remove! address-list "mary"))
+address-list
+@result{}
+(("bob" . "11 Newington Avenue") ("james" . "1a London Road"))
+@end example
+
+Note that, when @code{assq/v/oc-remove!} is used to modify an
+association list that has been constructed only using the corresponding
+@code{assq/v/oc-set!}, there can be at most one matching entry in the
+alist, so the question of multiple entries being removed in one go does
+not arise. If @code{assq/v/oc-remove!} is applied to an association
+list that has been constructed using @code{acons}, or an
+@code{assq/v/oc-set!} with a different level of equality, or any mixture
+of these, it removes only the first matching entry from the alist, even
+if the alist might contain further matching entries. For example:
+
+@example
+(define address-list '())
+(set! address-list (assq-set! address-list "mary" "11 Elm Street"))
+(set! address-list (assq-set! address-list "mary" "57 Pine Drive"))
+address-list
+@result{}
+(("mary" . "57 Pine Drive") ("mary" . "11 Elm Street"))
+
+(set! address-list (assoc-remove! address-list "mary"))
+address-list
+@result{}
+(("mary" . "11 Elm Street"))
+@end example
+
+In this example, the two instances of the string "mary" are not the same
+when compared using @code{eq?}, so the two @code{assq-set!} calls add
+two distinct entries to @code{address-list}. When compared using
+@code{equal?}, both "mary"s in @code{address-list} are the same as the
+"mary" in the @code{assoc-remove!} call, but @code{assoc-remove!} stops
+after removing the first matching entry that it finds, and so one of the
+"mary" entries is left in place.
+
+@deffn {Scheme Procedure} assq-remove! alist key
+@deffnx {Scheme Procedure} assv-remove! alist key
+@deffnx {Scheme Procedure} assoc-remove! alist key
+@deffnx {C Function} scm_assq_remove_x (alist, key)
+@deffnx {C Function} scm_assv_remove_x (alist, key)
+@deffnx {C Function} scm_assoc_remove_x (alist, key)
+Delete the first entry in @var{alist} associated with @var{key}, and return
+the resulting alist.
+@end deffn
+
+@node Sloppy Alist Functions
+@subsubsection Sloppy Alist Functions
+
+@code{sloppy-assq}, @code{sloppy-assv} and @code{sloppy-assoc} behave
+like the corresponding non-@code{sloppy-} procedures, except that they
+return @code{#f} when the specified association list is not well-formed,
+where the non-@code{sloppy-} versions would signal an error.
+
+Specifically, there are two conditions for which the non-@code{sloppy-}
+procedures signal an error, which the @code{sloppy-} procedures handle
+instead by returning @code{#f}. Firstly, if the specified alist as a
+whole is not a proper list:
+
+@example
+(assoc "mary" '((1 . 2) ("key" . "door") . "open sesame"))
+@result{}
+ERROR: In procedure assoc in expression (assoc "mary" (quote #)):
+ERROR: Wrong type argument in position 2 (expecting association list): ((1 . 2) ("key" . "door") . "open sesame")
+
+(sloppy-assoc "mary" '((1 . 2) ("key" . "door") . "open sesame"))
+@result{}
+#f
+@end example
+
+@noindent
+Secondly, if one of the entries in the specified alist is not a pair:
+
+@example
+(assoc 2 '((1 . 1) 2 (3 . 9)))
+@result{}
+ERROR: In procedure assoc in expression (assoc 2 (quote #)):
+ERROR: Wrong type argument in position 2 (expecting association list): ((1 . 1) 2 (3 . 9))
+
+(sloppy-assoc 2 '((1 . 1) 2 (3 . 9)))
+@result{}
+#f
+@end example
+
+Unless you are explicitly working with badly formed association lists,
+it is much safer to use the non-@code{sloppy-} procedures, because they
+help to highlight coding and data errors that the @code{sloppy-}
+versions would silently cover up.
+
+@deffn {Scheme Procedure} sloppy-assq key alist
+@deffnx {C Function} scm_sloppy_assq (key, alist)
+Behaves like @code{assq} but does not do any error checking.
+Recommended only for use in Guile internals.
+@end deffn
+
+@deffn {Scheme Procedure} sloppy-assv key alist
+@deffnx {C Function} scm_sloppy_assv (key, alist)
+Behaves like @code{assv} but does not do any error checking.
+Recommended only for use in Guile internals.
+@end deffn
+
+@deffn {Scheme Procedure} sloppy-assoc key alist
+@deffnx {C Function} scm_sloppy_assoc (key, alist)
+Behaves like @code{assoc} but does not do any error checking.
+Recommended only for use in Guile internals.
+@end deffn
+
+@node Alist Example
+@subsubsection Alist Example
+
+Here is a longer example of how alists may be used in practice.
+
+@lisp
+(define capitals '(("New York" . "Albany")
+ ("Oregon" . "Salem")
+ ("Florida" . "Miami")))
+
+;; What's the capital of Oregon?
+(assoc "Oregon" capitals) @result{} ("Oregon" . "Salem")
+(assoc-ref capitals "Oregon") @result{} "Salem"
+
+;; We left out South Dakota.
+(set! capitals
+ (assoc-set! capitals "South Dakota" "Pierre"))
+capitals
+@result{} (("South Dakota" . "Pierre")
+ ("New York" . "Albany")
+ ("Oregon" . "Salem")
+ ("Florida" . "Miami"))
+
+;; And we got Florida wrong.
+(set! capitals
+ (assoc-set! capitals "Florida" "Tallahassee"))
+capitals
+@result{} (("South Dakota" . "Pierre")
+ ("New York" . "Albany")
+ ("Oregon" . "Salem")
+ ("Florida" . "Tallahassee"))
+
+;; After Oregon secedes, we can remove it.
+(set! capitals
+ (assoc-remove! capitals "Oregon"))
+capitals
+@result{} (("South Dakota" . "Pierre")
+ ("New York" . "Albany")
+ ("Florida" . "Tallahassee"))
+@end lisp
+
+@node Hash Tables
+@subsection Hash Tables
+@tpindex Hash Tables
+
+@c FIXME::martin: Review me!
+
+Hash tables are dictionaries which offer similar functionality as
+association lists: They provide a mapping from keys to values. The
+difference is that association lists need time linear in the size of
+elements when searching for entries, whereas hash tables can normally
+search in constant time. The drawback is that hash tables require a
+little bit more memory, and that you can not use the normal list
+procedures (@pxref{Lists}) for working with them.
+
+@menu
+* Hash Table Examples:: Demonstration of hash table usage.
+* Hash Table Reference:: Hash table procedure descriptions.
+@end menu
+
+
+@node Hash Table Examples
+@subsubsection Hash Table Examples
+
+@c FIXME::martin: Review me!
+
+For demonstration purposes, this section gives a few usage examples of
+some hash table procedures, together with some explanation what they do.
+
+First we start by creating a new hash table with 31 slots, and
+populate it with two key/value pairs.
+
+@lisp
+(define h (make-hash-table 31))
+
+(hashq-create-handle! h 'foo "bar")
+@result{}
+(foo . "bar")
+
+(hashq-create-handle! h 'braz "zonk")
+@result{}
+(braz . "zonk")
+
+(hashq-create-handle! h 'frob #f)
+@result{}
+(frob . #f)
+@end lisp
+
+You can get the value for a given key with the procedure
+@code{hashq-ref}, but the problem with this procedure is that you
+cannot reliably determine whether a key does exists in the table. The
+reason is that the procedure returns @code{#f} if the key is not in
+the table, but it will return the same value if the key is in the
+table and just happens to have the value @code{#f}, as you can see in
+the following examples.
+
+@lisp
+(hashq-ref h 'foo)
+@result{}
+"bar"
+
+(hashq-ref h 'frob)
+@result{}
+#f
+
+(hashq-ref h 'not-there)
+@result{}
+#f
+@end lisp
+
+Better is to use the procedure @code{hashq-get-handle}, which makes a
+distinction between the two cases. Just like @code{assq}, this
+procedure returns a key/value-pair on success, and @code{#f} if the
+key is not found.
+
+@lisp
+(hashq-get-handle h 'foo)
+@result{}
+(foo . "bar")
+
+(hashq-get-handle h 'not-there)
+@result{}
+#f
+@end lisp
+
+There is no procedure for calculating the number of key/value-pairs in
+a hash table, but @code{hash-fold} can be used for doing exactly that.
+
+@lisp
+(hash-fold (lambda (key value seed) (+ 1 seed)) 0 h)
+@result{}
+3
+@end lisp
+
+@node Hash Table Reference
+@subsubsection Hash Table Reference
+
+@c FIXME: Describe in broad terms what happens for resizing, and what
+@c the initial size means for this.
+
+Like the association list functions, the hash table functions come in
+several varieties, according to the equality test used for the keys.
+Plain @code{hash-} functions use @code{equal?}, @code{hashq-}
+functions use @code{eq?}, @code{hashv-} functions use @code{eqv?}, and
+the @code{hashx-} functions use an application supplied test.
+
+A single @code{make-hash-table} creates a hash table suitable for use
+with any set of functions, but it's imperative that just one set is
+then used consistently, or results will be unpredictable.
+
+@sp 1
+Hash tables are implemented as a vector indexed by a hash value formed
+from the key, with an association list of key/value pairs for each
+bucket in case distinct keys hash together. Direct access to the
+pairs in those lists is provided by the @code{-handle-} functions.
+
+When the number of table entries goes above a threshold the vector is
+increased and the entries rehashed, to prevent the bucket lists
+becoming too long and slowing down accesses. When the number of
+entries goes below a threshold the vector is decreased to save space.
+
+@sp 1
+For the @code{hashx-} ``extended'' routines, an application supplies a
+@var{hash} function producing an integer index like @code{hashq} etc
+below, and an @var{assoc} alist search function like @code{assq} etc
+(@pxref{Retrieving Alist Entries}). Here's an example of such
+functions implementing case-insensitive hashing of string keys,
+
+@example
+(use-modules (srfi srfi-1)
+ (srfi srfi-13))
+
+(define (my-hash str size)
+ (remainder (string-hash-ci str) size))
+(define (my-assoc str alist)
+ (find (lambda (pair) (string-ci=? str (car pair))) alist))
+
+(define my-table (make-hash-table))
+(hashx-set! my-hash my-assoc my-table "foo" 123)
+
+(hashx-ref my-hash my-assoc my-table "FOO")
+@result{} 123
+@end example
+
+In a @code{hashx-} @var{hash} function the aim is to spread keys
+across the vector, so bucket lists don't become long. But the actual
+values are arbitrary as long as they're in the range 0 to
+@math{@var{size}-1}. Helpful functions for forming a hash value, in
+addition to @code{hashq} etc below, include @code{symbol-hash}
+(@pxref{Symbol Keys}), @code{string-hash} and @code{string-hash-ci}
+(@pxref{SRFI-13 Comparison}), and @code{char-set-hash} (@pxref{SRFI-14
+Predicates/Comparison}).
+
+Note that currently, unfortunately, there's no @code{hashx-remove!}
+function, which rather limits the usefulness of the @code{hashx-}
+routines.
+
+@sp 1
+@deffn {Scheme Procedure} make-hash-table [size]
+Create a new hash table, with an optional minimum vector @var{size}.
+
+When @var{size} is given, the table vector will still grow and shrink
+automatically, as described above, but with @var{size} as a minimum.
+If an application knows roughly how many entries the table will hold
+then it can use @var{size} to avoid rehashing when initial entries are
+added.
+@end deffn
+
+@deffn {Scheme Procedure} hash-ref table key [dflt]
+@deffnx {Scheme Procedure} hashq-ref table key [dflt]
+@deffnx {Scheme Procedure} hashv-ref table key [dflt]
+@deffnx {Scheme Procedure} hashx-ref hash assoc table key [dflt]
+@deffnx {C Function} scm_hash_ref (table, key, dflt)
+@deffnx {C Function} scm_hashq_ref (table, key, dflt)
+@deffnx {C Function} scm_hashv_ref (table, key, dflt)
+@deffnx {C Function} scm_hashx_ref (hash, assoc, table, key, dflt)
+Lookup @var{key} in the given hash @var{table}, and return the
+associated value. If @var{key} is not found, return @var{dflt}, or
+@code{#f} if @var{dflt} is not given.
+@end deffn
+
+@deffn {Scheme Procedure} hash-set! table key val
+@deffnx {Scheme Procedure} hashq-set! table key val
+@deffnx {Scheme Procedure} hashv-set! table key val
+@deffnx {Scheme Procedure} hashx-set! hash assoc table key val
+@deffnx {C Function} scm_hash_set_x (table, key, val)
+@deffnx {C Function} scm_hashq_set_x (table, key, val)
+@deffnx {C Function} scm_hashv_set_x (table, key, val)
+@deffnx {C Function} scm_hashx_set_x (hash, assoc, table, key, val)
+Associate @var{val} with @var{key} in the given hash @var{table}. If
+@var{key} is already present then it's associated value is changed.
+If it's not present then a new entry is created.
+@end deffn
+
+@deffn {Scheme Procedure} hash-remove! table key
+@deffnx {Scheme Procedure} hashq-remove! table key
+@deffnx {Scheme Procedure} hashv-remove! table key
+@deffnx {C Function} scm_hash_remove_x (table, key)
+@deffnx {C Function} scm_hashq_remove_x (table, key)
+@deffnx {C Function} scm_hashv_remove_x (table, key)
+Remove any association for @var{key} in the given hash @var{table}.
+If @var{key} is not in @var{table} then nothing is done.
+@end deffn
+
+@deffn {Scheme Procedure} hash key size
+@deffnx {Scheme Procedure} hashq key size
+@deffnx {Scheme Procedure} hashv key size
+@deffnx {C Function} scm_hash (key, size)
+@deffnx {C Function} scm_hashq (key, size)
+@deffnx {C Function} scm_hashv (key, size)
+Return a hash value for @var{key}. This is a number in the range
+@math{0} to @math{@var{size}-1}, which is suitable for use in a hash
+table of the given @var{size}.
+
+Note that @code{hashq} and @code{hashv} may use internal addresses of
+objects, so if an object is garbage collected and re-created it can
+have a different hash value, even when the two are notionally
+@code{eq?}. For instance with symbols,
+
+@example
+(hashq 'something 123) @result{} 19
+(gc)
+(hashq 'something 123) @result{} 62
+@end example
+
+In normal use this is not a problem, since an object entered into a
+hash table won't be garbage collected until removed. It's only if
+hashing calculations are somehow separated from normal references that
+its lifetime needs to be considered.
+@end deffn
+
+@deffn {Scheme Procedure} hash-get-handle table key
+@deffnx {Scheme Procedure} hashq-get-handle table key
+@deffnx {Scheme Procedure} hashv-get-handle table key
+@deffnx {Scheme Procedure} hashx-get-handle hash assoc table key
+@deffnx {C Function} scm_hash_get_handle (table, key)
+@deffnx {C Function} scm_hashq_get_handle (table, key)
+@deffnx {C Function} scm_hashv_get_handle (table, key)
+@deffnx {C Function} scm_hashx_get_handle (hash, assoc, table, key)
+Return the @code{(@var{key} . @var{value})} pair for @var{key} in the
+given hash @var{table}, or @code{#f} if @var{key} is not in
+@var{table}.
+@end deffn
+
+@deffn {Scheme Procedure} hash-create-handle! table key init
+@deffnx {Scheme Procedure} hashq-create-handle! table key init
+@deffnx {Scheme Procedure} hashv-create-handle! table key init
+@deffnx {Scheme Procedure} hashx-create-handle! hash assoc table key init
+@deffnx {C Function} scm_hash_create_handle_x (table, key, init)
+@deffnx {C Function} scm_hashq_create_handle_x (table, key, init)
+@deffnx {C Function} scm_hashv_create_handle_x (table, key, init)
+@deffnx {C Function} scm_hashx_create_handle_x (hash, assoc, table, key, init)
+Return the @code{(@var{key} . @var{value})} pair for @var{key} in the
+given hash @var{table}. If @var{key} is not in @var{table} then
+create an entry for it with @var{init} as the value, and return that
+pair.
+@end deffn
+
+@deffn {Scheme Procedure} hash-map->list proc table
+@deffnx {Scheme Procedure} hash-for-each proc table
+@deffnx {C Function} scm_hash_map_to_list (proc, table)
+@deffnx {C Function} scm_hash_for_each (proc, table)
+Apply @var{proc} to the entries in the given hash @var{table}. Each
+call is @code{(@var{proc} @var{key} @var{value})}. @code{hash-map->list}
+returns a list of the results from these calls, @code{hash-for-each}
+discards the results and returns an unspecified value.
+
+Calls are made over the table entries in an unspecified order, and for
+@code{hash-map->list} the order of the values in the returned list is
+unspecified. Results will be unpredictable if @var{table} is modified
+while iterating.
+
+For example the following returns a new alist comprising all the
+entries from @code{mytable}, in no particular order.
+
+@example
+(hash-map->list cons mytable)
+@end example
+@end deffn
+
+@deffn {Scheme Procedure} hash-for-each-handle proc table
+@deffnx {C Function} scm_hash_for_each_handle (proc, table)
+Apply @var{proc} to the entries in the given hash @var{table}. Each
+call is @code{(@var{proc} @var{handle})}, where @var{handle} is a
+@code{(@var{key} . @var{value})} pair. Return an unspecified value.
+
+@code{hash-for-each-handle} differs from @code{hash-for-each} only in
+the argument list of @var{proc}.
+@end deffn
+
+@deffn {Scheme Procedure} hash-fold proc init table
+@deffnx {C Function} scm_hash_fold (proc, init, table)
+Accumulate a result by applying @var{proc} to the elements of the
+given hash @var{table}. Each call is @code{(@var{proc} @var{key}
+@var{value} @var{prior-result})}, where @var{key} and @var{value} are
+from the @var{table} and @var{prior-result} is the return from the
+previous @var{proc} call. For the first call, @var{prior-result} is
+the given @var{init} value.
+
+Calls are made over the table entries in an unspecified order.
+Results will be unpredictable if @var{table} is modified while
+@code{hash-fold} is running.
+
+For example, the following returns a count of how many keys in
+@code{mytable} are strings.
+
+@example
+(hash-fold (lambda (key value prior)
+ (if (string? key) (1+ prior) prior))
+ 0 mytable)
+@end example
+@end deffn
+
+
+@c Local Variables:
+@c TeX-master: "guile.texi"
+@c End: