[Python-ideas] Re: Argumenting in favor of first()

Dec. 8, 2019


      
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On 8 Dec 2019, at 19:40, Guido van Rossum <guido@python.org> wrote:

We're not changing next(). It's too fundamental to change even subtly.
We might add itertools.first(), but not builtins.first(). This kind of functionality is not fundamental but it's easy to get slightly wrong (witness many hasty attempts in these threads).
itertools.first() should be implemented in C, but its semantics should be given by this (well, let me see if I can get it right):
def first(it, /, default=None):
    it = iter(it)
    try:
        return next(it)
    except StopIteration:
        return default
Why ban the use of keyword argument for the default value?

[Python-ideas] Re: Argumenting in favor of first()

Anders Hovmöller