[swift-users] If and Only If

[Andrew Clissold]

I would argue that "iff" is actually clearer and less brief, even though
it's fewer letters, because it forces you to stop and think "oh, they mean
it in the rigorous, mathematical sense of the phrase." And if you haven't
encountered it in math, you're far more likely to Google it. They
technically mean the same thing, but "if and only if" is much easier to
gloss over!

Andrew

On Mon, Feb 8, 2016 at 8:45 PM Don Wills via swift-users <
swift-users at swift.org> wrote:

> IMO, clarity is more important than brevity, particularly when novices and
> non-English speakers might not "get it".
>
> What's the harm in using "if and only if" instead of "iff"?  IMO, none.  I
> suggest using words, not a TLA.
>
> Don Wills
>
>
> On Feb 8, 2016, at 7:35 PM, zhaoxin肇鑫 via swift-users <
> swift-users at swift.org> wrote:
>
> I, as a none-native-English-speaker, do think iff as a type error at first
> for a long time. And I doubt it as I see it everywhere. But I have never
> look it up.
>
> I just use iff as if and do not think there is a much difference. I thank
> to Brian for he finally letting me know the real meaning. I think if itself
> means iff, but I am not computer major, so I can only represent as a layman.
>
> zhaoxin
>
> On Tue, Feb 9, 2016 at 2:18 AM, Erica Sadun via swift-users <
> swift-users at swift.org> wrote:
>
>> I personally wouldn't change it.
>>
>> A few thoughts:
>>
>> * It's a well known term of art among developers
>> * If you see "iff" more than once, you're going to be curious
>> * Hopefully you'll type "*what does iff mean*" into Google at that point
>> and Google will respond like this: http://imgur.com/1a7b3rp
>> * see also: http://ericasadun.com/2015/09/30/dear-erica-whats-iff/
>>
>> -- E
>>
>>
>> On Feb 7, 2016, at 9:16 PM, Brian Bauer via swift-users <
>> swift-users at swift.org> wrote:
>>
>> I apologize in advance if this subject has already been discussed and
>> decided (as far as I can tell, the mailing list archives go back only about
>> 60 days)…
>>
>> When running through the Swift Tour portion of the Swift eBook, on page
>> 10 there is a code snippet showing an example of the switch statement.
>> While typing that into an Xcode playground, I get a code completion popup
>> on the “hasSuffix” method and the documentation says “Returns true iff self
>> ends with suffix.”  This looks like a typo.  I know that it means “If and
>> Only If” but to a less experienced developer this is likely to be
>> misunderstood, especially as I can find no explanation for “iff” anywhere
>> in the documentation.
>>
>> The source of this documentation nugget is a comment in
>> /stdlib/public/core/StringLegacy.swift, so I think discussion of the topic
>> is relevant here.
>>
>> Swift is touted as being friendly to new programmers and I don’t think it
>> is reasonable to expect new programmers to understand “iff” and I also
>> don’t think it is reasonable to spend a paragraph explaining “iff” at the
>> beginning of an introduction to Swift, thus I suggest removing “iff” from
>> all code comments that are likely to become user-facing documentation (the
>> triple slash).  Or at the very least, user-facing documentation that is
>> likely to be read by beginners.
>>
>> A quick grep of the source gives me somewhere in the neighborhood of 130
>> instances of “iff” in a triple-slash comment, and I am more than happy to
>> make all of the changes and submit pull requests.  Before taking on that
>> work, however, I would like to know if such a change would be welcome or if
>> anyone has a better idea, etc.
>>
>> Thanks,
>> Brian
>>
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