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<p class="MsoNormal" style="margin-left:36.0pt">According to my table, we have two prefix `.`s. These are field accesses. Just like the tight infix positioning of `.`. So, (f a .b c .d e) means the exact same thing as (f a.b c.d e), which is, presumably (f
(a.b) (c.d) e).<o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">So `.x` behaves like a postfix operator with precedence
<i>tighter than function application</i>. Indeed, personally, I don’t like that!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Also I realise that it might be good to write<o:p></o:p></span></p>
<p class="Code"><span style="mso-fareast-language:EN-US"> xs .map double<o:p></o:p></span></p>
<p class="Code"><span style="mso-fareast-language:EN-US"> .filter isEven<o:p></o:p></span></p>
<p class="Code"><span style="mso-fareast-language:EN-US"> .map square<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">and that would indeed be what you could say with a postfix operator. It would parse as<o:p></o:p></span></p>
<p class="Code"><span style="mso-fareast-language:EN-US"> (((xs.map) double).filter isEven).map square<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Richard Eisenberg <rae@richarde.dev>
<br>
<b>Sent:</b> 10 December 2019 14:33<br>
<b>To:</b> Simon Peyton Jones <simonpj@microsoft.com><br>
<b>Cc:</b> Joachim Breitner <mail@joachim-breitner.de>; ghc-steering-committee@haskell.org<br>
<b>Subject:</b> Re: [ghc-steering-committee] RecordDotSyntax: please express a view<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Dec 10, 2019, at 2:27 PM, Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com">simonpj@microsoft.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:8.5pt;font-family:"Menlo-Regular",serif">| To be concrete, I propose this:<br>
<br>
Not concrete enough. I don't understand<span class="apple-converted-space"> </span><br>
<br>
| prefix with a ( before the .: field selector<br>
| otherwise: field access<br>
<br>
What does (f a .b c .d e) mean?</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">According to my table, we have two prefix `.`s. These are field accesses. Just like the tight infix positioning of `.`. So, (f a .b c .d e) means the exact same thing as (f a.b c.d e), which is, presumably (f (a.b) (c.d) e).<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Perhaps that's not what we like. But it is simple and comes straight from my table. And it is not too bad for programmers: prefix `.` is *just like* tight infix `.`. The only exception is at the beginning of a section, where tight-infix
does not make sense.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Richard<o:p></o:p></p>
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