NoneType List

[avi.e.gross at gmail.com]

Several of you have mentioned the role of history in the development of
languages and what the founders of a language were trying to improve.

As noted with PASCAL, some earlier languages strived to be different things
and in a certain sense, their procedures were perhaps seen as a safer and
better way to do things that languages like BASIC hade done with a GOSUB. On
top of that, there were concerns in a compiled language such as not leaving
an unused result on the stack when a function returned and even efficiency
considerations of several kinds. If a function returns a value, that value
has to persist beyond the lifetime of the function. It has to be in a kind
of memory different than where you can store values that go away. In a
procedure call, the compiler could use the fact that nothing is returned
other than through external variables. 

As noted, Guido started various languages, including Python, in a historical
context where he was not yet seeing things as "objects" in the way we often
do now. And he was trying to avoid some features often used in languages
like C for various reasons while keeping or extending others. I am not sure
about timing, but there have been many debates in the field about things
like programming without side effects and some insist that changing things
IN PLACE is a poor way to do things and instead things should be copied when
modified and so on.

So it well may be that allowing an inline sort or addition to a list was
added carefully in a way that made it very clear what you were doing and
seeing it more as a procedure call than a function that returned a value of
itself as Stefan points out.

But Python evolved and keeps evolving and like many biological organisms, to
some extent, ontogeny recapitulates phylogeny. It is really hard to get rid
of some early design choices even when a brand new design might allow a
cleaner design with more advantages. Python is becoming more like other
languages as it borrows from them and they borrow from it, and all borrow or
adapt from yet others. The result, frankly, can be a tad hard to understand
as the languages both converge and diverge only to converge again and some
simply go extinct or get totally re-done to adapt ...

-----Original Message-----
From: Python-list <python-list-bounces+avi.e.gross=gmail.com at python.org> On
Behalf Of Stefan Ram
Sent: Sunday, January 1, 2023 8:47 AM
To: python-list at python.org
Subject: Re: NoneType List

Thomas Passin <list1 at tompassin.net> writes:
>Guido had been working on the ABC language for some years before he 
>developed Python.  ABC was intended mainly as a teaching and 
>prototyping language.

  In those days, there used to be a language called "Pascal".
  Pascal had a dichotomy between "functions" and "procedures".
  A call to a function was intended to have a value.
  A call to a procedure was intended to have an effect.

  For some beginners, the difference between a value and
  and effect can be hard to grasp. So, Pascal's distinction
  helps to hammer that home. 

  Experienced programmers know the difference and do no longer
  require the effort of the language to teach it to them.

  The time when someone is a beginner and still struggles
  to understand the difference between values and effects
  usually is significantly shorter than the later time
  where he has understood it and is programming productively,
  so it might be better when the language is adapted to
  people who already have understood the difference.


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