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<p class="MsoNormal"><span style="font-size:12.0pt">Looks OK to me; but I’m no expert.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><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"> ghc-steering-committee <ghc-steering-committee-bounces@haskell.org>
<b>On Behalf Of </b>Simon Marlow<br>
<b>Sent:</b> 18 May 2018 09:24<br>
<b>To:</b> Joachim Breitner <mail@joachim-breitner.de><br>
<b>Cc:</b> ghc-steering-committee@haskell.org<br>
<b>Subject:</b> [ghc-steering-committee] Array resizing primitives (#121), proposal: accept with modifications<o:p></o:p></span></p>
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I propose that we accept <a href="https://github.com/ghc-proposals/ghc-proposals/pull/121" target="_blank">
https://github.com/ghc-proposals/ghc-proposals/pull/121</a><o:p></o:p></p>
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With one modification (below).<o:p></o:p></p>
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<br>
In summary, this proposal suggests adding primitives for resizing (shrinking or expanding) primitives mutable arrays of pointers. See the proposal for motivation. There would be two primitives per array type:<br>
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shrinkArray# :: MutableArray# s a -> Int# -> State# s -> State# s<br>
resizeArray# :: MutableArray# s a -> Int# -> a -> State# s -> (# State# s, MutableArray# s a #)<o:p></o:p></p>
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(these mirror the existing shrink and resize primitives we have for ByteArray#, with the same rationale)<o:p></o:p></p>
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<o:p> </o:p></p>
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The biggest downside is that we currently have<br>
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sizeOfMutableArray# :: MutableArray# s a -> Int #<o:p></o:p></p>
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which would need to be replaced by a stateful operation<o:p></o:p></p>
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<br>
getSizeOfMutableArray# :: MutableArray# s a -> State# s -> (# State# s, Int# #)<o:p></o:p></p>
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So we would need to deprecate the old primops, update any code we have that uses them, and clearly indicate the unsafety in the docs. But this has knock-on effects in Data.Primitive:<br>
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sizeofMutableArray :: MutableArray s a -> Int<o:p></o:p></p>
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<o:p> </o:p></p>
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this would need to be deprecated and replaced by a PrimMonad operation. The pure version would be unsafe in the sense that it could return the wrong size, and a future indexing operation relying on the incorrect size could access an out-of-bounds element.<o:p></o:p></p>
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<o:p> </o:p></p>
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Suggested modifications:<o:p></o:p></p>
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* Remove the ArrayArray# primitives, add UniftedArray# primitives instead (see <a href="https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0021-unlifted-array.rst">
https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0021-unlifted-array.rst</a>)<o:p></o:p></p>
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<o:p> </o:p></p>
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Cheers<o:p></o:p></p>
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Simon<o:p></o:p></p>
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<o:p> </o:p></p>
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On 1 May 2018 at 13:12, Joachim Breitner <<a href="mailto:mail@joachim-breitner.de" target="_blank">mail@joachim-breitner.de</a>> wrote:<o:p></o:p></p>
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Dear Committee,<br>
<br>
this is your secretary speaking:<br>
<br>
Array resizing primitives have been proposed by David Feuer:<br>
<a href="https://github.com/ghc-proposals/ghc-proposals/pull/121" target="_blank">https://github.com/ghc-proposals/ghc-proposals/pull/121</a><br>
<br>
I propose Simon Marlow as the shepherd.<br>
<br>
Simon, please reach consensus as described in<br>
<a href="https://github.com/ghc-proposals/ghc-proposals#committee-process" target="_blank">https://github.com/ghc-proposals/ghc-proposals#committee-process</a><br>
<br>
I suggest you make a recommendation, in a new e-mail thread with the<br>
proposal number in the subject, about the decision, maybe point out<br>
debatable points, and assume that anyone who stays quiet agrees with<br>
you.<br>
<br>
Thanks,<br>
<span class="gmail-hoenzb"><span style="color:#888888">-- </span></span><span style="color:#888888"><br>
<span class="gmail-hoenzb">Joachim Breitner</span><br>
<span class="gmail-hoenzb"> <a href="mailto:mail@joachim-breitner.de">mail@joachim-breitner.de</a></span><br>
<span class="gmail-hoenzb"> <a href="http://www.joachim-breitner.de/" target="_blank">
http://www.joachim-breitner.de/</a></span><br>
</span><br>
_______________________________________________<br>
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<a href="https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee" target="_blank">https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee</a><o:p></o:p></p>
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<o:p> </o:p></p>
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