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<p class="MsoNormal" style="margin-left:36.0pt">that the mechanism for preventing things like reordering operations or spurious sharing is shared in common between ST and IO via State#<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Yes. It’s pure data dependency, no more and no less. Operations in both ST and IO take a State# token as input, and produce one as output. So of course to get the
input one, all preceding operations must be done first. Simple!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> ghc-devs [mailto:ghc-devs-bounces@haskell.org]
<b>On Behalf Of </b>Christopher Allen<br>
<b>Sent:</b> 03 February 2016 23:30<br>
<b>To:</b> ghc-devs@haskell.org<br>
<b>Subject:</b> Guarantees for ST and IO shared in common?<o:p></o:p></span></p>
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Underlying ST is: GHC.Prim.State# s -> (# GHC.Prim.State# s, a #)<br clear="all">
<o:p></o:p></p>
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Underlying IO is: GHC.Prim.State# GHC.Prim.RealWorld<o:p></o:p></p>
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-> (# GHC.Prim.State# GHC.Prim.RealWorld, a #)<o:p></o:p></p>
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Based on the (very helpful!) conversation I had on the #ghc IRC channel, it seems to me that the mechanism for preventing things like reordering operations or spurious sharing is shared in common between ST and IO via State#. Is this accurate? I believe the
exception is how RealWorld is used w/ IO but we can put that off for this question.<o:p></o:p></p>
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If anyone could confirm this understanding that would be helpful. If anyone could point out exceptions to this notion, I'd very much appreciate that as well.<o:p></o:p></p>
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<o:p> </o:p></p>
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Thanks again for everyone's time.<o:p></o:p></p>
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<o:p> </o:p></p>
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-- <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:6.0pt;margin-right:0cm;margin-bottom:6.0pt;margin-left:0cm">
Chris Allen<o:p></o:p></p>
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<span style="font-size:9.5pt">Currently working on </span><a href="https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fhaskellbook.com&data=01%7c01%7csimonpj%40064d.mgd.microsoft.com%7c437e21b733ab4fa4895908d32cf1fd68%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=PPVWa%2bCUw8gEWIOVEyJNcOKuGGmZBtfvXg0wsA2jS2Y%3d" target="_blank">http://haskellbook.com</a><o:p></o:p></p>
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