<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><br class=""><blockquote type="cite" class=""><div class="">Am 08.11.2017 um 21:25 schrieb John McCall <<a href="mailto:rjmccall@apple.com" class="">rjmccall@apple.com</a>>:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;"><div class=""><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: 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-size-adjust: auto; -webkit-text-stroke-width: 0px;"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;">My point is: The proposed filterMap isn’t a combination of map and filter at all — or can you build it just out of map & filter, like flatMap is constructed from map & flatten?</div></div></blockquote><div 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;" class=""><br class=""></div><span 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; float: none; display: inline !important;" class="">You can built it out of map and filter:</span></div><div class=""><br class=""></div><div class=""> func filterMap<T>(_ fn: (Element) -> U?) -> [U] {</div><div class=""> return map(fn).filter { $0 != nil }.map { $0! }</div><div class=""> }</div></div></div></blockquote></div>True, but it’s not what I asked for — and it should rather be called „mapFilterMapForceUnwrap“, shouldn’t it? ;-)<div class="">The thing is that people who don’t fully understand flatMap (those that are the target group for the proposal) probably just use it because „it does a transformation and filters out nil (and nil is evil)“.</div><div class="">Renaming the function to filterMap hardens that misconception:</div><div class="">As you sample shows, filterMap is not like flatMap — the latter is honest („flatten the result of map“) the other isn’t („filter the result of map“ only strips the nils, but doesn’t change the return type)</div><div class=""><br class=""></div><div class="">So I think it’s better to keep flatMap, or replace it with something that doesn’t pretend to be a plain filter.</div></body></html>