[Python-3000] Python 3000 Status Update (Long!)

[Steve Howell]

--- Bill Janssen <janssen at parc.com> wrote:

> > Multiple additions (with "+") mean "sum" in
> > arithmetic, but you can't generalize that to
> strings
> > and text processing.  The "+" operator for any two
> > strings is not about adding--it's about
> > joining/concatenating.  So multiple applications
> of
> > "+" on strings aren't a sum.  They're just a
> longer
> > join/concatenation. 
> 
> Hmmm.  Your argument would be more pursuasive if you
> couldn't do this
> in Python:
> 
> >>> a = "abc" + "def" + "ghi" + "jkl"
> >>> a
> 'abcdefghijkl'
> >>> 
> 
> The real problem with "sum", I think, is that the
> parameter list is
> ill-conceived (perhaps because it was added before
> variable length
> parameter lists were?).  It should be
> 
>   sum(*operands)
> 
> not
> 
>   sum(operands, initialvalue=?)
> 
> It should amount to "map(+, operands)".
> 

I think you were missing my point, which is that sum
doesn't and shouldn't necessarily have the same
semantics as map(+).

"Sum," in both Python and common English usage, is a
generalization of arithmetic addition, but it's not a
generalization of applying operators that happen to be
spelled "+."

There's no natural English punctuation for
concatenation, and Python's choice of "+" could be
called mostly arbitrary (although it's consistent with
a few other programming languages.)  The following
operators can mean concatenation in various
programming languages:

   +
   .
   &
   ||

Oddly, in English a common way to concatenate words is
with the "-" character.  It means a hyphen in English,
and it's use to create multi-word-thingies, but the
operator itself is also a subtraction operator.  So
you could speciously argue that when you concatenate
words in English, you're doing a difference, but under
your proposed Python, you'd be doing a sum.



   


       
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