> I've taken the time to run a test, going through milion numbers (several
> times) using:
>
> for i in arr { if i % 2 == 0 { continue } }
> for i in arr where i % 2 == 0 { }
> for i in arr.filter({ $0 % 2 == 0 }) { }
> for i in arr.lazy.filter({ $0 % 2 == 0 }) { }
>
> Results:
>
> - plain for loop with if-continue: 27.19 seconds (+1.76%)
> - with where: 26.72 seconds (+0.00%)
> - .filter: 44.73 seconds (+67.40%)
> - .lazy.filter: 31.66 seconds (+18.48%)
This is great data. I have a hard time imagining a little compiler work
couldn't make if-continue as fast as for-where, but lazy.filter might be a
taller order for it, and optimizing plain filter could actually change behavior.
A month or two ago, I actually fell into the "just use the higher-order
functions" camp on this question, but I've been rethinking that more and more
lately. Between the trailing closure incompatibility, the need to remember to
use `lazy` to get decent performance, and now the noticeable speed difference
even *with* lazy, I'm no longer convinced that answer is good enough.
(Though I do think `while` is probably too niche to bother with as a
first-class feature, and I am open to if-continue on the `where` clause.)
--
Brent Royal-Gordon
Architechies
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