I think that the "strings are an iterable of strings", i.e. an iterable of iterables onto infinity... is the last remaining common dynamic type issue with Python.

However, I'd like to see the "solution" be a character type, rather than making strings not iterable, so iterating a string would yield chars, and chars would not be strings themselves, and not be iterable (or a sequence at all).

This would be analogous to other iterables -- they can contain iterables, but if you keep iterating (or indexing), eventually you get to a "scalar", non iterable value.

This works well, for, e.g. numpy, where each index or iteration reduces the rank of the array until you get a scalar.

And we don't seem to have constant problems with functions that expect an iterable of, say, numbers getting passed a single number and thinning it's an iterable of numbers.

But, as stated by the OP, it'll be a long path to get there, so I doubt it's worth it.

In any case, there should be some consensus on what the long term goal is before we start proposing ways to get there.

-CHB

On Sat, Feb 22, 2020 at 9:12 PM Ricky Teachey <ricky@teachey.org> wrote:

It's always been in the back of my mind that directly iterable strings are very often more trouble than they are worth. But I also agree that changing it would probably be extremely disruptive (and also might be more trouble than it's worth).

I've only been at it for about 3 years, but because of iterable strings I always seem to regret not using a function like this in many contexts:
def iter_nostr(iterable):
    if isinstance(iterable, str):
        raise TypeError(f"iterable cannot be a str")
    yield from iter(iterable)
The nature of my coding work is a lot of parsing of different kinds of text files and so I've had to write a lot of functions that are meant to take in an iterable of strings. So the biggest context that comes to mind is to guard against future me mistakenly sending a string into functions that are intended to work with iterables of strings. I always seem to find a way to do this, with all kinds of head scratching results depending on the situation. I learned early on that if I don't include a guard like this, I'm going to pay for it later.

---
Ricky.

"I've never met a Kentucky man who wasn't either thinking about going home or actually going home." - Happy Chandler
On Sat, Feb 22, 2020 at 11:09 PM Steven D'Aprano <steve@pearwood.info> wrote:
On Sun, Feb 23, 2020 at 01:28:35AM -0000, Steve Jorgensen wrote:

> Another issue is one of consistency. A string is not a sequence of
> length-1 strings.

Isn't it? It sure looks like a sequence of length-1 (sub)strings to me.

Of course, strings can also be views as a sequence of paragraphs, lines,
words, or any other sort of substring you like. Hypertalk allowed you to
read strings in arbitrarily nested "chunks":

get the last character of the first word of the third line of text

with similar syntax for writing and iteration. One might argue that
there's nothing particularly useful about characters, and treating
strings as sequences of words, lines etc could be more useful. But I
don't think we can argue that strings aren't sequences of
substrings, including characters.

> The length-1 strings created by iterating are more
> like slices than members.

They certainly aren't members (attributes). You can't access a
particular substring using dot notation:

# Give me the first char in the string
c = string.0 # Syntax error.

So substrings aren't attributes/members. What would you name them? The
same applies to lists and other sequences as well.

--
Steven
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