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Comment by andybak | Hacker News Reader

With regard to C-style for loops - other than familiarity - why?

It always struck me as a fairly warty syntax.

Consider Python where you usually do:

    for item in iterator

If you want an integer sequence it's:

   for integer in range(1, 100)

and for those rare occurrences where you need an integer index as well:

    for index, item in enumerate(iterator)

Swift seems to have a similar approach. Why would you ever want the C-style iterators?

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For the simple case with a single iterator, yes the C-style for loop isn't as concise. However, there are lots of real-world situations where there is not a single iterator (e.g. looping through 2 arrays). Having to go back to 'while(boolean) { }' loops with initializers outside of the loop and incrementors at strange places inside the loop is much more confusing and error prone.

You can use the zip function to loop through 2 collections.

`for (l, r) in zip(c1, c2) {`

It is not simply motivated by making code concise, I would say `for num in collection.reverse()` is less error prone and clearer than `for (var i = collection.count; i >= 0; i--) { var num = collection[i] ... }`

The reverse collection iterator is computed lazily too, so there is no little perf overhead

Sometimes having those counting variables available is needed. You can use enumerate now but it introduces a lot of noise as now everything is a tuple with a number. It just makes expressing some algorithms messier and less readable although in general for sure "new style" loop is more readable and less bug prone.

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