Part of SF patch #1513870 (the still relevant part) -- add reduce() to

functools, and adjust docs etc.

4 files changed, 17 insertions, 67 deletions

diff --git a/Doc/howto/doanddont.tex b/Doc/howto/doanddont.tex
index a105ca1..df3ca34 100644
--- a/Doc/howto/doanddont.tex
+++ b/Doc/howto/doanddont.tex
@@ -289,19 +289,7 @@ There are also many useful builtin functions people seem not to be
 aware of for some reason: \function{min()} and \function{max()} can
 find the minimum/maximum of any sequence with comparable semantics,
 for example, yet many people write their own
-\function{max()}/\function{min()}. Another highly useful function is
-\function{reduce()}. A classical use of \function{reduce()}
-is something like
-
-\begin{verbatim}
-import sys, operator
-nums = map(float, sys.argv[1:])
-print reduce(operator.add, nums)/len(nums)
-\end{verbatim}
-
-This cute little script prints the average of all numbers given on the
-command line. The \function{reduce()} adds up all the numbers, and
-the rest is just some pre- and postprocessing.
+\function{max()}/\function{min()}.
 
 On the same note, note that \function{float()}, \function{int()} and
 \function{long()} all accept arguments of type string, and so are
diff --git a/Doc/lib/libfuncs.tex b/Doc/lib/libfuncs.tex
index 65b0bf5..c9e35b5 100644
--- a/Doc/lib/libfuncs.tex
+++ b/Doc/lib/libfuncs.tex
@@ -836,19 +836,6 @@ class Parrot(object):
 \end{verbatim}
 \end{funcdesc}
 
-\begin{funcdesc}{reduce}{function, sequence\optional{, initializer}}
-  Apply \var{function} of two arguments cumulatively to the items of
-  \var{sequence}, from left to right, so as to reduce the sequence to
-  a single value.  For example, \code{reduce(lambda x, y: x+y, [1, 2,
-  3, 4, 5])} calculates \code{((((1+2)+3)+4)+5)}.  The left argument,
-  \var{x}, is the accumulated value and the right argument, \var{y},
-  is the update value from the \var{sequence}.  If the optional
-  \var{initializer} is present, it is placed before the items of the
-  sequence in the calculation, and serves as a default when the
-  sequence is empty.  If \var{initializer} is not given and
-  \var{sequence} contains only one item, the first item is returned.
-\end{funcdesc}
-
 \begin{funcdesc}{reload}{module}
   Reload a previously imported \var{module}.  The
   argument must be a module object, so it must have been successfully
@@ -1058,8 +1045,6 @@ class C:
   The \var{sequence}'s items are normally numbers, and are not allowed
   to be strings.  The fast, correct way to concatenate sequence of
   strings is by calling \code{''.join(\var{sequence})}.
-  Note that \code{sum(range(\var{n}), \var{m})} is equivalent to
-  \code{reduce(operator.add, range(\var{n}), \var{m})}
   \versionadded{2.3}
 \end{funcdesc}
 
diff --git a/Doc/lib/libfunctools.tex b/Doc/lib/libfunctools.tex
index 33a6f52..034143a 100644
--- a/Doc/lib/libfunctools.tex
+++ b/Doc/lib/libfunctools.tex
@@ -51,6 +51,19 @@ two:
   \end{verbatim}
 \end{funcdesc}
 
+\begin{funcdesc}{reduce}{function, sequence\optional{, initializer}}
+  Apply \var{function} of two arguments cumulatively to the items of
+  \var{sequence}, from left to right, so as to reduce the sequence to
+  a single value.  For example, \code{reduce(lambda x, y: x+y, [1, 2,
+  3, 4, 5])} calculates \code{((((1+2)+3)+4)+5)}.  The left argument,
+  \var{x}, is the accumulated value and the right argument, \var{y},
+  is the update value from the \var{sequence}.  If the optional
+  \var{initializer} is present, it is placed before the items of the
+  sequence in the calculation, and serves as a default when the
+  sequence is empty.  If \var{initializer} is not given and
+  \var{sequence} contains only one item, the first item is returned.
+\end{funcdesc}
+
 \begin{funcdesc}{update_wrapper}
 {wrapper, wrapped\optional{, assigned}\optional{, updated}}
 Update a wrapper function to look like the wrapped function. The optional
diff --git a/Doc/tut/tut.tex b/Doc/tut/tut.tex
index 1b08a8e..6f6fe6f 100644
--- a/Doc/tut/tut.tex
+++ b/Doc/tut/tut.tex
@@ -1893,8 +1893,8 @@ use \method{pop()} with \code{0} as the index.  For example:
 
 \subsection{Functional Programming Tools \label{functional}}
 
-There are three built-in functions that are very useful when used with
-lists: \function{filter()}, \function{map()}, and \function{reduce()}.
+There are two built-in functions that are very useful when used with
+lists: \function{filter()} and \function{map()}.
 
 \samp{filter(\var{function}, \var{sequence})} returns a sequence
 consisting of those items from the
@@ -1934,42 +1934,6 @@ is shorter than another).  For example:
 >>> map(add, seq, seq)
 [0, 2, 4, 6, 8, 10, 12, 14]
 \end{verbatim}
-
-\samp{reduce(\var{function}, \var{sequence})} returns a single value
-constructed by calling the binary function \var{function} on the first two
-items of the sequence, then on the result and the next item, and so
-on.  For example, to compute the sum of the numbers 1 through 10:
-
-\begin{verbatim}
->>> def add(x,y): return x+y
-...
->>> reduce(add, range(1, 11))
-55
-\end{verbatim}
-
-If there's only one item in the sequence, its value is returned; if
-the sequence is empty, an exception is raised.
-
-A third argument can be passed to indicate the starting value.  In this
-case the starting value is returned for an empty sequence, and the
-function is first applied to the starting value and the first sequence
-item, then to the result and the next item, and so on.  For example,
-
-\begin{verbatim}
->>> def sum(seq):
-...     def add(x,y): return x+y
-...     return reduce(add, seq, 0)
-... 
->>> sum(range(1, 11))
-55
->>> sum([])
-0
-\end{verbatim}
-
-Don't use this example's definition of \function{sum()}: since summing
-numbers is such a common need, a built-in function
-\code{sum(\var{sequence})} is already provided, and works exactly like
-this.
 \versionadded{2.3}
 
 \subsection{List Comprehensions}
@@ -2739,7 +2703,7 @@ standard module \module{__builtin__}\refbimodindex{__builtin__}:
  'id', 'int', 'intern', 'isinstance', 'issubclass', 'iter',
  'len', 'license', 'list', 'locals', 'long', 'map', 'max', 'min',
  'object', 'oct', 'open', 'ord', 'pow', 'property', 'quit', 'range',
- 'reduce', 'reload', 'repr', 'reversed', 'round', 'set',
+ 'reload', 'repr', 'reversed', 'round', 'set',
  'setattr', 'slice', 'sorted', 'staticmethod', 'str', 'sum', 'super',
  'tuple', 'type', 'unichr', 'unicode', 'vars', 'xrange', 'zip']
 \end{verbatim}