+@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 Pretty Printing
@chapter Pretty Printing
@lisp
(pretty-print '(define (foo) (lambda (x)
-(cond ((zero? x) #t) ((negative? x) -x) (else (if (= x 1) 2 (* x x x)))))))
+(cond ((zero? x) #t) ((negative? x) -x) (else
+(if (= x 1) 2 (* x x x)))))))
@print{}
(define (foo)
(lambda (x)
(else (if (= x 1) 2 (* x x x))))))
@end lisp
-@deffn {Scheme Procedure} pretty-print obj [port]
+@deffn {Scheme Procedure} pretty-print obj [port] [keyword-options]
Print the textual representation of the Scheme object @var{obj} to
@var{port}. @var{port} defaults to the current output port, if not
given.
+
+The further @var{keyword-options} are keywords and parameters as
+follows,
+
+@table @asis
+@item @nicode{#:display?} @var{flag}
+If @var{flag} is true then print using @code{display}. The default is
+@code{#f} which means use @code{write} style. (@pxref{Writing})
+
+@item @nicode{#:per-line-prefix} @var{string}
+Print the given @var{string} as a prefix on each line. The default is
+no prefix.
+
+@item @nicode{#:width} @var{columns}
+Print within the given @var{columns}. The default is 79.
+@end table
@end deffn
Beware: Since @code{pretty-print} uses it's own write procedure, it's
@end defun
+@node Queues
+@chapter Queues
+@cindex Queues
+@tindex Queues
+
+@noindent
+The functions in this section are provided by
+
+@example
+(use-modules (ice-9 q))
+@end example
+
+This module implements queues holding arbitrary scheme objects and
+designed for efficient first-in / first-out operations.
+
+@code{make-q} creates a queue, and objects are entered and removed
+with @code{enq!} and @code{deq!}. @code{q-push!} and @code{q-pop!}
+can be used too, treating the front of the queue like a stack.
+
+@sp 1
+
+@deffn {Scheme Procedure} make-q
+Return a new queue.
+@end deffn
+
+@deffn {Scheme Procedure} q? obj
+Return @code{#t} if @var{obj} is a queue, or @code{#f} if not.
+
+Note that queues are not a distinct class of objects but are
+implemented with cons cells. For that reason certain list structures
+can get @code{#t} from @code{q?}.
+@end deffn
+
+@deffn {Scheme Procedure} enq! q obj
+Add @var{obj} to the rear of @var{q}, and return @var{q}.
+@end deffn
+
+@deffn {Scheme Procedure} deq! q
+@deffnx {Scheme Procedure} q-pop! q
+Remove and return the front element from @var{q}. If @var{q} is
+empty, a @code{q-empty} exception is thrown.
+
+@code{deq!} and @code{q-pop!} are the same operation, the two names
+just let an application match @code{enq!} with @code{deq!}, or
+@code{q-push!} with @code{q-pop!}.
+@end deffn
+
+@deffn {Scheme Procedure} q-push! q obj
+Add @var{obj} to the front of @var{q}, and return @var{q}.
+@end deffn
+
+@deffn {Scheme Procedure} q-length q
+Return the number of elements in @var{q}.
+@end deffn
+
+@deffn {Scheme Procedure} q-empty? q
+Return true if @var{q} is empty.
+@end deffn
+
+@deffn {Scheme Procedure} q-empty-check q
+Throw a @code{q-empty} exception if @var{q} is empty.
+@end deffn
+
+@deffn {Scheme Procedure} q-front q
+Return the first element of @var{q} (without removing it). If @var{q}
+is empty, a @code{q-empty} exception is thrown.
+@end deffn
+
+@deffn {Scheme Procedure} q-rear q
+Return the last element of @var{q} (without removing it). If @var{q}
+is empty, a @code{q-empty} exception is thrown.
+@end deffn
+
+@deffn {Scheme Procedure} q-remove! q obj
+Remove all occurences of @var{obj} from @var{q}, and return @var{q}.
+@var{obj} is compared to queue elements using @code{eq?}.
+@end deffn
+
+@sp 1
+@cindex @code{q-empty}
+The @code{q-empty} exceptions described above are thrown just as
+@code{(throw 'q-empty)}, there's no message etc like an error throw.
+
+A queue is implemented as a cons cell, the @code{car} containing a
+list of queued elements, and the @code{cdr} being the last cell in
+that list (for ease of enqueuing).
+
+@example
+(@var{list} . @var{last-cell})
+@end example
+
+@noindent
+If the queue is empty, @var{list} is the empty list and
+@var{last-cell} is @code{#f}.
+
+An application can directly access the queue list if desired, for
+instance to search the elements or to insert at a specific point.
+
+@deffn {Scheme Procedure} sync-q! q
+Recompute the @var{last-cell} field in @var{q}.
+
+All the operations above maintain @var{last-cell} as described, so
+normally there's no need for @code{sync-q!}. But if an application
+modifies the queue @var{list} then it must either maintain
+@var{last-cell} similarly, or call @code{sync-q!} to recompute it.
+@end deffn
+
+
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