food for thought - swift 5 released - bottom types, string interpolation, and stuff.

[aliak]

On Friday, 12 April 2019 at 02:13:12 UTC, Walter Bright wrote:
> On 4/11/2019 6:24 PM, Timon Gehr wrote:
>>>    bool isOdd(int i) { return i & 1; }
>>>
>>> Filling the standard library with trivia is not a good idea.
>> 
>> Yes, if it is used often enough across many projects, adding 
>> functions with a simple implementation can be a very good 
>> idea. The main point is to standardize the function name and 
>> avoid duplicated equivalent code in everyone's personal util 
>> libraries.
>
> That would make sense if there was some application-specific 
> higher level meaning to oddness, such as maybe the low bit 
> being used as a flag. But there isn't when it is named "isOdd".
>

I've used n % 2 == 0 millions of times in GUI logic. Applying 
properties to things that are row'ed-out. Games is another one - 
very common. Fuzzy matching another one. isOdd would've made the 
call site a lot more clear.

>
>>> Not knowing about a common operator is not a reason to add 
>>> library functions.
>> No, but there can be other reasons.
>
> That was the reason given. I'm open to hearing a better one.

Using n & 1 has always been a hack for oddness. It says nothing 
about what your code is doing. The average programmer would look 
at it and have to think about what's happening there.

I do understand what you mean about being a bit suspicious about 
isOdd though when seeing it in code. But I think the same would 
apply to abs if we had not grown up with it being in math.h. We'd 
be doing "n>0?n:-n" or "(n+(n>>31))^(n>>31)" - or the more saner 
would write their own. And then when someone comes and tries to 
add abs to a standard library functions one could also say "not 
knowing about [a] common operator[s] is not a reason to add a 
library functions".

But after all this time working on products as low level as 
drivers to as high level as web apps, the three things that have 
been the most important have been readability, maintainability, 
and correctness.