Hi,<br><br>I&#39;m trying to speed up Data.Time (the time package) &#39;cause my program is spending a very substantial fraction of time manipulating dates.<br><br>I decided to start with strictifying and unpacking the date/time types, as there&#39;s no point in having them be lazy and I indeed had a lot of allocation in date/time arithmetic in my performance profile.<br>
<br>data UTCTime = UTCTime {<br>    utctDay :: {-# UNPACK #-} !Day,<br>    utctDayTime :: {-# UNPACK #-} !DiffTime<br>}<div><br></div><div>(unpacks and strictness mine)<br><div><br></div><div>newtype Day = ModifiedJulianDay {toModifiedJulianDay :: Integer} </div>
<div>newtype DiffTime = MkDiffTime Pico</div><div><br></div><div>And Pico is also essentially a newtype for Integer.</div><div><br></div><div>So, I&#39;m getting warnings on this definition of UTCTime. </div><div>QUESTION: Is it the case that I can only UNPACK primitive fields, and not even their newtypes?</div>
<div><br></div><div><div>Data\Time\Clock\UTC.hs:30:16:</div><div>    Warning: Ignoring unusable UNPACK pragma on the</div><div>             first argument of `UTCTime&#39;</div><div>    In the definition of data constructor `UTCTime&#39;</div>
<div>    In the data type declaration for `UTCTime&#39;</div><div><br></div><div>Data\Time\Clock\UTC.hs:30:16:</div><div>    Warning: Ignoring unusable UNPACK pragma on the</div><div>             second argument of `UTCTime&#39;</div>
<div>    In the definition of data constructor `UTCTime&#39;</div><div>    In the data type declaration for `UTCTime&#39;</div><div><br></div><div><br></div><div><br></div>-- <br>Eugene Kirpichov<br>Principal Engineer, Mirantis Inc. <a href="http://www.mirantis.com/">http://www.mirantis.com/</a><br>
Editor, <a href="http://fprog.ru/">http://fprog.ru/</a><br><br></div></div>