<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Sep 15, 2017, at 4:50 AM, Brent Royal-Gordon <<a href="mailto:brent@architechies.com" class="">brent@architechies.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=us-ascii" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><blockquote type="cite" class=""><div class="">On Sep 12, 2017, at 12:48 PM, Adam Kemp 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 class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">@IBAction func buttonDidClick(sender:AnyObject) {</div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"> beginAsync {</div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"> let image = await processImage(downloadImage(), resize: self.resizeSwitch.isOn)</div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"> displayImage(image)</div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"> }</div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">}</div></div></blockquote><br class=""></div><div class="">Would it be possible to actually fix this? That is, make the code covered by the `await` evaluate synchronous subexpressions first, such that the code sample above is equivalent to this?</div><div class=""><br class=""></div><div class=""><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>@IBAction func buttonDidClick(sender:AnyObject) {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span> beginAsync {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let $temp1 = self.resizeSwitch.isOn</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let $temp2 = await downloadImage()</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span> let image = await processImage($temp2, resize: $temp1)</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span> displayImage(image)</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span> }</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>}</div></div></div></div></blockquote></div><br class=""><div class="">That violates the defined order of evaluation for function arguments. You could also write code in which the (async) first argument function call has side effects that alter the result of the second argument expression. I’m not saying that’s good code, but it’s possible, and the language defines the order of evaluation so that code like that will have a predictable behavior.</div></body></html>