<div dir="ltr"><br><div class="gmail_extra">On Thu, Feb 7, 2013 at 5:41 PM, Ross Paterson <span dir="ltr"><<a href="mailto:ross@soi.city.ac.uk" target="_blank">ross@soi.city.ac.uk</a>></span> wrote:<br><div class="gmail_quote">
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="im">On Thu, Feb 07, 2013 at 02:49:40PM -0800, Conal Elliott wrote:<br>
</div><div class="im">> I make some use of arrow notation, though sadly I often have to avoid<br>
> it because my (pseudo-)"arrows" don't have arr. I'd love to see a<br>
> variant that has restricted expressiveness in exchange for arr-freeness.<br>
<br>
</div>It's hard to imagine arrow notation without arr (or at least<br>
contravariance in the first argument of the "arrow") because forming<br>
expressions using the local environment is so central to it. That is,<br>
I can't imagine what things you are trying to write in that situation.<br></blockquote><div><br>What I have in mind is a small collection of methods including fst & snd (and similarly for sums) that could be defined via arr but could instead form the basis of translating restricted arrow notation for (pseudo-)arrows that don't support arr.<br>
<br>I keep running into these pseudo-arrows in practical work. The reliance of arrow notation on arr means that I can't use arrow notation, and my code is terribly difficult to read.<br><br></div><div>-- Conal<br></div>
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