<div dir="auto">If this is for convenience for arrows, isn't it better implemented as?:<div dir="auto"><br></div><div dir="auto">dup :: Arrow a => a b (b,b)</div><div dir="auto">dup = id &&& id</div></div><br><div class="gmail_quote"><div dir="ltr">2018년 10월 28일 (일) 15:03, Dan Burton <<a href="mailto:danburton.email@gmail.com">danburton.email@gmail.com</a>>님이 작성:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr">There is precedent in the arrow literature for calling this function "dup". For example, on page 55 of this paper:</div><div dir="ltr"><a href="http://homepages.inf.ed.ac.uk/wadler/papers/arrows-jfp/arrows-jfp.pdf" target="_blank" rel="noreferrer">http://homepages.inf.ed.ac.uk/wadler/papers/arrows-jfp/arrows-jfp.pdf</a><br><br clear="all"><div><div dir="ltr" class="m_-1748704609077661093gmail_signature">-- Dan Burton</div></div><br><input name="virtru-metadata" type="hidden" value="{"email-policy":{"state":"closed","expirationUnit":"days","disableCopyPaste":false,"disablePrint":false,"disableForwarding":false,"enableNoauth":false,"expires":false,"isManaged":false},"attachments":{},"compose-id":"5","compose-window":{"secure":false}}"></div><br><div class="gmail_quote"><div dir="ltr">On Sun, Oct 28, 2018 at 12:48 AM David Feuer <<a href="mailto:david.feuer@gmail.com" target="_blank" rel="noreferrer">david.feuer@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="auto"><div>I'm not opposed. Should this be called dup or diagonal? What about larger tuples?</div><div><br></div><div>Side note:</div><div>\x -> (x,x) = join (,)</div><div><br><div class="gmail_quote"><div dir="ltr">On Sat, Oct 27, 2018, 6:03 PM Ivan Perez <<a href="mailto:ivan.perez@keera.co.uk" target="_blank" rel="noreferrer">ivan.perez@keera.co.uk</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear all,<br>
<br>
The function \x -> (x,x) is very convenient when working with arrows.<br>
<br>
Would it be appropriate to add it to Data.Tuple?<br>
<br>
Cheers,<br>
<br>
Ivan<br>
<br>
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