<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>-1 for using -> and => to mean different types of functions, not-pure and pure respectively. In fact I dislike using symbols unless they are really well known. Keywords read a lot better. <br><br>Sent from my iPad</div><div><br>On 22 Dec 2015, at 8:37 AM, Joe Groff via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br><br></div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html charset=us-ascii"><br class=""><div><blockquote type="cite" class=""><div class="">On Dec 21, 2015, at 12:20 PM, T.J. Usiyan via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">I have been thinking about this proposal since the list opened up. I think that @read(none|only) should be considered as an alternative. Just as in clang and the optimizer annotations @read(none) would be the attribute described and @read(only) could read global variables but could not write. Is it possible to generate a runtime error if we guarantee that function A is pure, only to call it and 'find out' that it isn't? If we can, then do try syntax could be considered. </div></div></blockquote></div><br class=""><div class="">Another approach here is an effects system. If a pure function were spelled `(T) => U`, then `readonly` could be expressed as `(T) reads => U`, and (T) -> U could remain as a synonym for (T) reads, writes => U, in the spirit of encouraging immutability without punishing mutability.</div><div class=""><br class=""></div><div class="">-Joe</div>
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