From 4a6ee5b830d688f1c12972d0e89965ca66316cd0 Mon Sep 17 00:00:00 2001 From: "Richard M. Stallman" Date: Tue, 26 May 1998 20:36:22 +0000 Subject: *** empty log message *** --- lispref/lists.texi | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) (limited to 'lispref') diff --git a/lispref/lists.texi b/lispref/lists.texi index bdc94dc015a..e20baaea5c2 100644 --- a/lispref/lists.texi +++ b/lispref/lists.texi @@ -32,9 +32,10 @@ the whole list. Lists in Lisp are not a primitive data type; they are built up from @dfn{cons cells}. A cons cell is a data object that represents an -ordered pair. It records two Lisp objects, one labeled as the @sc{car}, -and the other labeled as the @sc{cdr}. These names are traditional; see -@ref{Cons Cell Type}. @sc{cdr} is pronounced ``could-er.'' +ordered pair. It holds, or ``points to,'' two Lisp objects, one labeled +as the @sc{car}, and the other labeled as the @sc{cdr}. These names are +traditional; see @ref{Cons Cell Type}. @sc{cdr} is pronounced +``could-er.'' A list is a series of cons cells chained together, one cons cell per element of the list. By convention, the @sc{car}s of the cons cells are @@ -82,10 +83,10 @@ made from two cons cells: Each pair of boxes represents a cons cell. Each box ``refers to'', ``points to'' or ``contains'' a Lisp object. (These terms are -synonymous.) The first box, which is the @sc{car} of the first cons -cell, contains the symbol @code{tulip}. The arrow from the @sc{cdr} of -the first cons cell to the second cons cell indicates that the @sc{cdr} -of the first cons cell points to the second cons cell. +synonymous.) The first box, which describes the @sc{car} of the first +cons cell, contains the symbol @code{tulip}. The arrow from the +@sc{cdr} box of the first cons cell to the second cons cell indicates +that the @sc{cdr} of the first cons cell is the second cons cell. The same list can be illustrated in a different sort of box notation like this: @@ -668,8 +669,9 @@ different element. @defun setcar cons object This function stores @var{object} as the new @sc{car} of @var{cons}, -replacing its previous @sc{car}. It returns the value @var{object}. -For example: +replacing its previous @sc{car}. In other words, it changes the +@sc{car} slot of @var{cons} to point to @var{object}. It returns the +value @var{object}. For example: @example @group @@ -770,7 +772,9 @@ x2: | @defun setcdr cons object This function stores @var{object} as the new @sc{cdr} of @var{cons}, -replacing its previous @sc{cdr}. It returns the value @var{object}. +replacing its previous @sc{cdr}. In other words, it changes the +@sc{cdr} slot of @var{cons} to point to @var{object}. It returns the +value @var{object}. @end defun Here is an example of replacing the @sc{cdr} of a list with a @@ -797,7 +801,7 @@ x You can delete elements from the middle of a list by altering the @sc{cdr}s of the cons cells in the list. For example, here we delete the second element, @code{b}, from the list @code{(a b c)}, by changing -the @sc{cdr} of the first cell: +the @sc{cdr} of the first cons cell: @example @group @@ -968,7 +972,7 @@ each time you run it! Here is what happens: This function reverses the order of the elements of @var{list}. Unlike @code{reverse}, @code{nreverse} alters its argument by reversing the @sc{cdr}s in the cons cells forming the list. The cons cell that -used to be the last one in @var{list} becomes the first cell of the +used to be the last one in @var{list} becomes the first cons cell of the value. For example: @@ -985,7 +989,7 @@ x @result{} (4 3 2 1) @end group @group -;; @r{The cell that was first is now last.} +;; @r{The cons cell that was first is now last.} x @result{} (1) @end group @@ -1249,7 +1253,7 @@ for another way to add an element to a list stored in a variable. An @dfn{association list}, or @dfn{alist} for short, records a mapping from keys to values. It is a list of cons cells called -@dfn{associations}: the @sc{car} of each cell is the @dfn{key}, and the +@dfn{associations}: the @sc{car} of each cons cell is the @dfn{key}, and the @sc{cdr} is the @dfn{associated value}.@footnote{This usage of ``key'' is not related to the term ``key sequence''; it means a value used to look up an item in a table. In this case, the table is the alist, and -- cgit v1.2.1