[Tim]
>> Every suggestion here so far has satisfied that, if S is a non-empty set,
>>
>> assert next(iter(S)) is first(S)
>>
>> succeeds. That is, `first()` is _defined_ by reference to iteration
>> order. It's "the first" in that order (hence the name).
[Stephen J. Turnbull <turnbull.stephen...@u.tsukuba.ac.jp>]
> The problem I'm concerned with is that sometimes users' definitions of
> words differ from a computer language's definitions of words. That's
> why I used the word "natural", which doesn't really have much to do
> with the way a computer language defines things, but frequently
> features in human thought.
>
> Whether that potential difference matters here is an empirical
> question.
>
> Theoretically, I can say "Explicit is better than implicit."
> I.e., the call to 'iter' tells us exactly what order is being used.
But hasn't it already been settled by experience? There is nothing
unique about `first(set)` implicitly appealing to iteration order. A
set passed as the iterable to _any_ itertools function does exactly
the same:
>>> import itertools
>>> list(itertools.zip_longest(set("abcde"), range(5))) # can vary from run to
>>> run
[('a', 0), ('e', 1), ('c', 2), ('d', 3), ('b', 4)]
>>> list(itertools.compress(set("abcde"), [1]*5)) # but is consistent within a
>>> run
['a', 'e', 'c', 'd', 'b']
>>> list(itertools.takewhile(lambda x: True, set("abcde")))
['a', 'e', 'c', 'd', 'b']
So do, e.g., some builtins:
>>> list(map(ord, set("abcde")))
[97, 101, 99, 100, 98]
>>> [ord(ch) for ch in set("abcde")]
[97, 101, 99, 100, 98]
> That's *my* opinion in this case, and I don't hold *you* to it just
> because I'm quoting you. (I am amused, though.)
I just don't see the potential for "new" bafflement if itertools.first
works exactly the same way as itertools.anything_else _has_ worked, in
this respect, all along. Give users some credit. Programming is
baffling, period, at first. But to those who persist, nothing becomes
truly unbearable ;-)
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