<div dir="auto">Or 'join (,)'</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jul 16, 2019, 09:26 Zemyla <<a href="mailto:zemyla@gmail.com">zemyla@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="auto">id &&& id</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jul 16, 2019, 10:58 Ignat Insarov <<a href="mailto:kindaro@gmail.com" target="_blank" rel="noreferrer">kindaro@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello.<br>
<br>
I wonder if there is a function like \x -> (x, x) in the standard libraries.<br>
<br>
I looked up in Hoogle. It gave me links:<br>
<br>
1. <a href="https://hackage.haskell.org/package/utility-ht/docs/Data-Tuple-HT.html#v:double" rel="noreferrer noreferrer noreferrer" target="_blank">https://hackage.haskell.org/package/utility-ht/docs/Data-Tuple-HT.html#v:double</a><br>
2. <a href="https://hackage.haskell.org/package/extra/docs/Data-Tuple-Extra.html#v:dupe" rel="noreferrer noreferrer noreferrer" target="_blank">https://hackage.haskell.org/package/extra/docs/Data-Tuple-Extra.html#v:dupe</a><br>
3. <a href="https://hackage.haskell.org/package/relude/docs/Relude-Extra-Tuple.html#v:dupe" rel="noreferrer noreferrer noreferrer" target="_blank">https://hackage.haskell.org/package/relude/docs/Relude-Extra-Tuple.html#v:dupe</a><br>
<br>
None of these is to the standard library. I wonder if there is an<br>
intentional omission for some important reason? If not, I think this<br>
function should be added to Data.Tuple.<br>
<br>
I know some of the persons that make decisions here like Category<br>
theory, so I point out this function is mentioned in Categories for<br>
the Working Mathematician, as δ, the diagonal function, on page 3<br>
(second edition), although set with angular brackets.<br>
<br>
Have a great day.<br>
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