gh-107017: Rework the Fibonacci example.

[TommyUnreal]

Rework the example to be simple to follow and also the concepts needed for that are now explained one by one with their own shorter examples.

Needs proofread. Please comment with your ideas for improvement.

• Issue: remove the assumptions from The tutorial #107017

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📚 Documentation preview 📚: https://cpython-previews--107132.org.readthedocs.build/

[evildmp]

.:: will produce a full-stop and a colon:

.:

One or the other. I suggest losing the full-stop.

[evildmp]

"in example" > "for example"

[TommyUnreal]

What I wanted to say is that "in the example below the condition is the following expression a < 10", but that is no longer present in the examples. I will rework that.

[evildmp]

I suggest using while, to draw attention to it.

[evildmp]

"... the parser"

[evildmp]

Again, here we have a full-stop and a colon in the output.

[evildmp]

This is an elegant touch.

[TommyUnreal]

Thank you :)

[evildmp]

And I like the way that the example illustrates the value of using end - no need to explain, the example does it much more effectively. This will stick in someone's mind.

[CaedenPH]

I understand that this utilities the print sep param, however this is nor explained nor inferred, so to a beginner it may be confusing

Perhaps it could be beneficial to show off f-strings like

Suggested change

	... print('', a, '', end='->')
	... print(f'{a} ->', end='')

Or to keep end as ->

Suggested change

	... print('', a, '', end='->')
	... print(f'{a} ', end="->")

[evildmp]

I very strongly prefer the original print('', a, '', end='->'), which reduces the punctuation the learner has to deal with to a minimum, and emphasises instead the connection between more easily assimilated things, like the English word "end" and the "arrow" ("->").

Showing off f-strings while demonstrating a different functionality introduces unnecessary cognitive burden. Two different kinds of quotes and two different kinds of brackets requires a lot of parsing and stopping. I don't think this is the right solution here.

[TommyUnreal]

My reasoning: As this is an Introduction chapter, I wanted to keep the number of introduced concepts to the minimum. There are ways to code this better, but it is not formally wrong. The default separator is already shown in the example above and this just builds on that, so it's hopefully not confusing to the reader.

[CaedenPH]

Suggested change

	... count = count - 1 # lower the value by one with each repetition
	... count = count - 1 # decrement the value each iteration

[evildmp]

I would strongly prefer "decrease the value by one".

The reason is that many people will not be familiar with the word "decrement", it's used very little in English outside technical contexts.

[CaedenPH]

Needs to be 1

[TommyUnreal]

Is this a doctest bug?

[evildmp]

I would strongly prefer "decrease the value by one".

The reason is that many people will not be familiar with the word "decrement", it's used very little in English outside technical contexts.

[evildmp]

I very strongly prefer the original print('', a, '', end='->'), which reduces the punctuation the learner has to deal with to a minimum, and emphasises instead the connection between more easily assimilated things, like the English word "end" and the "arrow" ("->").

Showing off f-strings while demonstrating a different functionality introduces unnecessary cognitive burden. Two different kinds of quotes and two different kinds of brackets requires a lot of parsing and stopping. I don't think this is the right solution here.

[CaedenPH]

Other than these grammatical mistakes, looks like a good change to me

[SylvainDe]

Very nice touch! Here are 2 cosmetic details

[SylvainDe]

Typo here

[SylvainDe]

We already know the print function ?

[hugovk]

A suggestion and some little wording things, otherwise looks good!

[hugovk]

Suggested change

	To do that we need to utilize three following concepts.
	To do that we need to use the three following concepts.

Let's use the plain English "use" instead of "utilize".

[hugovk]

Suggested change

	A *multiple assignment* of variables us allows to set values of more than one
	A *multiple assignment* of variables us allows to set the values of more than one

[hugovk]

Suggested change

	variable on a single line. Notice that if the value assignment is a
	variable on a single line. Notice that if the value assignment is an

[hugovk]

Suggested change

	The :keyword:`while` loop is example of a repeating cycle. It performs
	The :keyword:`while` loop is an example of a repeating cycle. It performs

[hugovk]

Suggested change

	of count. As soon as the variable ``count`` reaches the value 5, the
	of ``count``. As soon as the variable ``count`` reaches the value 5, the

[hugovk]

Suggested change

	>>> count = 0; # define variable to which we will be adding 1 in a loop
	>>> count = 0 # define variable to which we will be adding 1 in a loop

[hugovk]

The example above uses a one-liner: while count < 5: count = count + 1

Let's use indentation in the example, to match the text. Something like this?

Suggested change

	>>> while count < 5: count = count + 1 # hit enter one more time to start the loop
	...
	>>> count # when count reached value of 5, while loop finished
	5
	Note that block inside the ``while`` loop, or *body* of the loop is *indented*.
	>>> while count < 5:
	... count = count + 1 # hit enter one more time to start the loop
	...
	>>> count # when count reached value of 5, while loop finished
	5
	Note that block inside the ``while`` loop, or *body* of the loop is *indented*.

[hugovk]

Suggested change

	parentheses ``()``. In simplest form, like ``print(a, b)``, the arguments
	are positional, meaning the function processes them in the same order
	parentheses ``()``. In its simplest form, like ``print(a, b)``, the arguments
	are positional, meaning the function processes them in the same order

[hauntsaninja]

Thanks for working on this! As compared to the version on the left hand side, I found presenting all the concepts up front in detailed sections a little intimidating. I preferred seeing the four lines we're building towards first, and then an explanation of what's going on.