[Python-ideas] Simpler syntax for basic iterations

[Stephen J. Turnbull]

Andre Roberge writes:

 > >> While Python is an ideal language for beginners, the Python
 > >> construct for iterations, namely
 > >>
 > >> for var in range(n):
 > >>      # suite
 > >>
 > >> does require a variable and is needlessly complicated for
 > >> beginners.  A simpler construct like:
 > >>
 > >> repeat n:    # n is a specific integer
 > >>      # suite
 > >>
 > >> would be useful to have in such contexts.  Other keywords could
 > >> be chosen instead of "repeat" used above.

I have no objection to such a language, but it ain't Python.  It's an
important principle of Python that "There's one- and preferably only
one -obvious way to do it."  While the parenthetical "only one" is
violated on occasion, it's still considered important.

 > >> for var in range(n):
 > >>      # suite

I just don't have a problem with this.

It seems to me that on the occasions when I've taught programming[2],
I've always had the most success when the student has a concrete
problem in mind (sometimes they need to write programs to complete
another project, but also when they take programming as a required
course).  Take the traditional make a square in turtle graphics:

    right = -90
    length = 10
    def make_square (turtle):
        for side in ('top', 'right', 'bottom', 'left'):
            turtle.forward(length)
            turtle.turn(right)

Do you really have students writing code like

    for _ in range(20):
        print('yes')

where the repetition is exact?

 > It is unfortunate, given the original CP4E goal, but not altogether
 > unexpected -- although, I do find the word "mutilate" to be a bit
 > strong.

The goal called "CP4E" as I understood it was to give the *full* power
of "computer programming" to "everyone", not to just provide a taste.
The *power* of computer programming comes from small but expressive
vocabularies, it seems to me.

 > The reason is that I don't believe in students having to unlearn
 > something (like a special repeat syntax available only in a
 > specific environment) when they might have been under the
 > impression that it was standard Python syntax.

So call the new language "Childrens-Python"[1] if you like.<wink/>  Or
"Woma" (which is a bit bigger than Children's Python) if that's too
close to "Python".

 > Furthermore, it might instill doubt in their mind about other
 > construct they have learn (are they standard? ... or were they too
 > something only available in the specific environment?...)

So what?  If they're going to do computer programming after they leave
your class, they're surely going to encounter "specific environments".
So many times I've typed an example into the interpreter only to
discover that the author didn't explicitly import a function or
identifier from a module, but it looks like it could be a builtin I
hadn't used before.

 > I'll have a look.  However, as I mentioned above, I'm not keen on
 > introducing what amounts to a potentially completely different
 > language.

It doesn't look to me like that's what Terry is talking about, though.
I suppose that as usual there will be a "consenting adults" convention
that "you could do that with this hook, but please, *not* in front of
the children!"  Rather, for cases where you don't need the full power
of Python's expression syntax, you could eliminate parentheses from
function calls and that kind of thing.

 > Python is a fantastic language for beginners (and advanced)
 > programmers ...  I was just hoping to make it a tiny bit easier to
 > learn for complete beginners who are introduced to Python in visual
 > environments (like the turtle module or a Karel the Robot clone).

At the cost of requiring every Python programmer to beware of a new
and infrequently syntax.


Footnotes: 
[1]  http://www.snakeranch.com.au/snake-profiles/childrens-python/

[2]  Always at the college level or above, though.