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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Harendra<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">That comes as a surprise to me. Could you possibly make a repo case, and say what version of the compiler does, and does not, specialise the function?<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">File it as a ticket … to me it looks like a bug.<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">Thanks<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"> ghc-devs <ghc-devs-bounces@haskell.org>
<b>On Behalf Of </b>Harendra Kumar<br>
<b>Sent:</b> 06 September 2021 14:11<br>
<b>To:</b> ghc-devs@haskell.org<br>
<b>Subject:</b> Question about specialization<o:p></o:p></span></p>
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Hi GHC devs,<o:p></o:p></p>
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<o:p> </o:p></p>
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I have a simple program using the streamly library, as follows, the whole code is in the same module:<o:p></o:p></p>
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<o:p> </o:p></p>
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{-# INLINE iterateState #-}<br>
{-# SPECIALIZE iterateState :: Int -> SerialT (StateT Int IO) Int #-}<br>
iterateState :: MonadState Int m => Int -> SerialT m Int<br>
iterateState n = do<br>
x <- get<br>
if x > n<br>
then do<br>
put (x - 1)<br>
iterateState n<br>
else return x<o:p></o:p></p>
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<o:p> </o:p></p>
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main :: IO ()<br>
main = do<br>
State.evalStateT (S.drain (iterateState 0)) 100000<o:p></o:p></p>
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<o:p> </o:p></p>
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Earlier the SPECIALIZE pragma was not required on iterateState, but after some refactoring in the library (the monad bind of SerialT changed a bit), this program now requires a SPECIALIZE on iterateState to trigger specialization, just INLINE also does not
help.<o:p></o:p></p>
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<o:p> </o:p></p>
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My question is whether this may be expected in some conditions or is this something which can be considered a bug in the compiler? I am also curious what specifically could have made the compiler not specialize this anymore, is it the size of the function or
some other threshold?<o:p></o:p></p>
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<o:p> </o:p></p>
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Thanks,<o:p></o:p></p>
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Harendra<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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