<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div><br></div><div><br>On 29 Oct 2017, at 3:01 pm, Mike Kluev <<a href="mailto:mike.kluev@gmail.com">mike.kluev@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">On 29 October 2017 at 14:02, Johannes Weiß <span dir="ltr"><<a href="mailto:johannesweiss@apple.com" target="_blank">johannesweiss@apple.com</a>></span> wrote:<div><br><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div dir="auto">Definitely not arguing with that. But there are (valid?) cases when you want a recursive closure which doesn’t have a native recursion mechanism and then `fix` can be useful I’d argue. I think more straightforward than<div><br></div><div><span class="gmail-"><blockquote type="cite"><blockquote type="cite"><div><blockquote type="cite"><blockquote type="cite"><font color="#000000"><span style="background-color:rgba(255,255,255,0)">recursive.c = { x in<br> (x == 0) ? 1 : x * recursive.c(x - 1)<br> }</span></font></blockquote></blockquote></div></blockquote></blockquote><div><br></div></span></div></div></blockquote><div><br></div><div><div><div class="gmail_extra"><div class="gmail_quote"><div>you can do without "recursive.c":</div><div><br></div><div><div>var factorial: ((Int) -> Int)!</div><div><br></div><div>factorial = { n in</div><div><span style="white-space:pre"> </span>n == 0 ? 1 : n * factorial(n - 1)</div><div>}</div></div></div></div></div></div></div></div></div></div></div></blockquote><div><br></div>That’s nicer, thanks!<div><br><blockquote type="cite"><div><div dir="ltr"><div><div class="gmail_extra"><div class="gmail_quote"><div><div><div class="gmail_extra"><div class="gmail_quote"><div><div><br></div><div>factorial(5) // 120</div></div><div><br></div><div> <br></div></div></div></div></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div dir="auto"><div><span class="gmail-"><div></div></span><div>. But fortunately have local functions, I can only recall wanting a recursive closure once.</div><span class="gmail-HOEnZb"><font color="#888888"><div><br></div></font></span></div></div></blockquote><div><br></div><div>in down to earth practical programming even if i didn't have local functions i probably wouldn't bother abusing closures to implement recursion, would just used what's available: methods. and if there is some extra state to pass from the outer scopes, well, so be it, either via parameters of via some instance variables, etc. wasn't too much of a problem in good old C/C++. in a way, knowing exact state you want to pass and passing it explicitly organises the code and the reasoning about it.</div><div><br></div><div>Mike</div><div><br></div></div></div></div></div>
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