<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div><br></div><div><span>1. Evaluation</span></div><div><span>Initially I was hesitant but now I support this change.</span></div><div><span style="background-color: rgba(255, 255, 255, 0);">The C-style for-loop is syntactic baggage (the semicolons do not separate its parts very well) and suffers from the problem that it is imperative, i.e. The loop variable is just that, a variable, and therefore will not work as expected when captured in closures that are executed later, e.g. in a GCD queue.</span></div><div><span style="background-color: rgba(255, 255, 255, 0);">There might be some corner cases where the C-style for-loop cannot be easily replaced with a for-loop or a while-loop in the presence of several continue statements, which is why I originally proposed to Swiftify the C-style for-loop instead of removing it, but I haven't seen a concrete one yet and I am optimistic that good solutions can be found even for these cases by refactorings e.g. extracting the loop body into a function and replacing continue with return. If someone has a concrete case for which that does not apply for some reasons I'd be interested to see that case and reconsider.</span></div><div><br><span>2. Significance</span></div><div><span>The C-style for-loop does not fit syntactically and its use is limited. In most cases the for-in loop is much better suited and more expressive and for the remaining few cases a while-loop can be used. </span></div><div><span></span><br>3. Direction of Swift<br><span>This proposal fits the philosophy of Swift with regards to readability and safety because the alternatives are more expressive and readable.</span><br><br>4. Comparisons<br>I have long experience with mostly Smalltalk, Haskell, Swift and Java, and from earlier times with C, C++, Python and Ruby. Furthermore I follow the development of many languages with modern constructs closely, e.g. Scala, Ceylon, Clojure and others and have a strong interest in programming language design.</div><div>Most of these languages, i.e. all except Swift, Java and of course C and C++, do not have a C-style for-loop. They typically do have more expressive loops similar to the for-in loop of Swift (or more powerful, e.g. Scala's for-expression which is similar to Haskells monadic do-notation).</div><div>Dylan has an iterating for-loop which improves on the C-style for-loop by introducing a new binding for the loop "variable" on each iteration, which might look like follows in a Swiftified syntax:</div><div><br></div><div><b>for</b> i = 0 <b>then</b> i + 1 <b>while</b> i < limit { ... }</div><div><div><span style="background-color: rgba(255, 255, 255, 0);"><b>for</b> i = 0 <b>then</b> i + 1 <b>until</b> i == limit { ... }</span></div></div><div><br></div><div>which effectively introduces a let binding in the init clause scoped to the loop, an expression to replace the binding with for the next iteration and a while or until clause which is checked before each iteration.</div><div><br></div><div>I would propose this as an alternative to removing the C-style for-loop if a review makes a convincing case that an incremental loop is still needed.</div><div><span></span><br>5. Effort<br><span>I read the proposal carefully, read the discussion in the mailing list, checked two large Java codebases (large systems for logistics) for occurences of for-loops and did only find trivial ones. Furthermore I checked textbooks </span><span style="background-color: rgba(255, 255, 255, 0);">for their looping constructs</span>, e.g. "Concepts, techniques and models of computer programming" by van Roy and Haridi (highly recommended!), .</div><div><br></div></body></html>