<div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial"><div>> That is simply misspelled for your intent.<br><span id="transmark" style="display: none; width: 0px; height: 0px;"></span><br></div>Take a look at the following function in Haskell (GHC) Data.Set<br> minView :: Set a -> Maybe (a, Set a)<br>We always want the new set after a immutable set pop().<br> "e = a.pop()" is fine for mutable set, but not for immutable case.<br> we need "e, a = a.pop()" to update "a".<br><br><br><br><br><br><div style="position:relative;zoom:1"></div><div id="divNeteaseMailCard"></div><br>ÔÚ 2017-03-01 01:23:54£¬"David Mertz" <mertz@gnosis.cx> дµÀ£º<br> <blockquote id="isReplyContent" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Tue, Feb 28, 2017 at 5:59 AM, ÓïÑÔÆÆËé´¦ <span dir="ltr"><<a href="mailto:mlet_it_bew@126.com" target="_blank">mlet_it_bew@126.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="line-height:1.7;color:#000000;font-size:14px;font-family:Arial">bad example:<br> a = set()<br> a.add(1) # return None; "a" changed<br> e = a.pop();<br></div></blockquote><div><br></div><div>That is simply misspelled for your intent.</div><div><br></div></div></div><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div class="gmail_extra"><div class="gmail_quote"><div><font face="monospace, monospace">a = set()</font></div></div></div></blockquote><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div class="gmail_extra"><div class="gmail_quote"><div><font face="monospace, monospace">a |= {1}</font></div></div></div></blockquote><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div class="gmail_extra"><div class="gmail_quote"><div><font face="monospace, monospace">e = a.pop()</font></div></div></div></blockquote><div class="gmail_extra"><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature">Keeping medicines from the bloodstreams of the sick; food <br>from the bellies of the hungry; books from the hands of the <br>uneducated; technology from the underdeveloped; and putting <br>advocates of freedom in prisons. Intellectual property is<br>to the 21st century what the slave trade was to the 16th.<br></div>
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