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</o:shapelayout></xml><![endif]--></head><body lang=NL link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>David, <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>I tried your first suggestion $!. Nothing changed.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>When I tried ‘Right <$> evaluate (TE.decodeUtf8 bufferStrict)’ success. handleException catches the exception. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>I don’t understand why. Maybe the documentation for the evaluate function below has to do with it:<o:p></o:p></span></p><p style='margin:0cm;margin-bottom:.0001pt;background:white'><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'>There is a subtle difference between </span><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/Control-Exception-Base.html#v:evaluate" title=Control.Exception.Base><span lang=EN-US style='color:#AB6954'>evaluate</span></a></span></code><code><span lang=EN-US style='font-size:10.0pt;color:black'> x</span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'> and </span><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/Control-Monad.html#v:return" title=Control.Monad><span lang=EN-US style='color:#AB6954'>return</span></a></span></code><code><span lang=EN-US style='font-size:10.0pt;color:black'> </span></code><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/Prelude.html#v:-36--33-" title=Prelude><span lang=EN-US style='color:#AB6954'>$!</span></a></span></code><code><span lang=EN-US style='font-size:10.0pt;color:black'> x</span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'>, analogous to the difference between </span><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/Control-Exception-Base.html#v:throwIO" title=Control.Exception.Base><span lang=EN-US style='color:#AB6954'>throwIO</span></a></span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'> and </span><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/Control-Exception-Base.html#v:throw" title=Control.Exception.Base><span lang=EN-US style='color:#AB6954'>throw</span></a></span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'>. If the lazy value </span><code><span lang=EN-US style='font-size:10.0pt;color:black'>x</span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'> throws an exception, </span><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/Control-Monad.html#v:return" title=Control.Monad><span lang=EN-US style='color:#AB6954'>return</span></a></span></code><code><span lang=EN-US style='font-size:10.0pt;color:black'> </span></code><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/Prelude.html#v:-36--33-" title=Prelude><span lang=EN-US style='color:#AB6954'>$!</span></a></span></code><code><span lang=EN-US style='font-size:10.0pt;color:black'> x</span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'> will fail to return an </span><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/System-IO.html#t:IO" title=System.IO><span lang=EN-US style='color:#AB6954'>IO</span></a></span></code><code><span style='font-size:10.0pt;color:black'> </span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'>action and will throw an exception instead. </span><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/Control-Exception-Base.html#v:evaluate" title=Control.Exception.Base><span lang=EN-US style='color:#AB6954'>evaluate</span></a></span></code><code><span lang=EN-US style='font-size:10.0pt;color:black'> x</span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'>, on the other hand, always produces an </span><code><span style='font-size:10.0pt;color:black'><a href="http://hackage.haskell.org/package/base-4.12.0.0/docs/System-IO.html#t:IO" title=System.IO><span lang=EN-US style='color:#AB6954'>IO</span></a></span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'> action; that action will throw an exception upon <em><span style='font-family:"Arial",sans-serif'>execution</span></em> iff </span><code><span lang=EN-US style='font-size:10.0pt;color:black'>x</span></code><span lang=EN-US style='font-size:10.0pt;font-family:"Arial",sans-serif;color:black'> throws an exception upon <em><span style='font-family:"Arial",sans-serif'>evaluation</span></em>.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>I don’t fully understand this, but evaluate works. Thanks!<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'>Kees<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal style='line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#DCDCAA'>readCDFile</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>::</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>FilePath</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>-></span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>FilePath</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>-></span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>IO</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> (</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>Either</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>String</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>T</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'>.</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>Text</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'>)<o:p></o:p></span></p><p class=MsoNormal style='line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'>readCDFile baseDir fn = </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#C586C0'>do</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'><o:p></o:p></span></p><p class=MsoNormal style='line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> catch ( </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#C586C0'>do</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> <o:p></o:p></span></p><p class=MsoNormal style='line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> buffer <- B.readFile (combine baseDir fn) </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#6A9955'>--reads strict the whole file</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'><o:p></o:p></span></p><p class=MsoNormal style='line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> </span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#569CD6'>let</span><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> bufferStrict = B.toStrict buffer<o:p></o:p></span></p><p class=MsoNormal style='margin-left:35.4pt;text-indent:35.4pt;line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'>return $ Right $! TE.decodeUtf8 bufferStrict -- this doesn’t work <o:p></o:p></span></p><p class=MsoNormal style='margin-left:35.4pt;text-indent:35.4pt;line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'>Right <$> evaluate (TE.decodeUtf8 bufferStrict) –- this does <o:p></o:p></span></p><p class=MsoNormal style='margin-left:35.4pt;text-indent:35.4pt;line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'>liftM Right $ evaluate (TE.decodeUtf8 bufferStrict) – this works too <o:p></o:p></span></p><p class=MsoNormal style='line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'> ) exceptionHandler<o:p></o:p></span></p><p class=MsoNormal style='line-height:14.25pt;background:#1E1E1E'><span lang=EN-US style='font-size:10.5pt;font-family:"Courier New";color:#D4D4D4'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Van:</span></b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri",sans-serif'> David Fox [mailto:dsf@seereason.com] <br><br></span><span lang=EN-US><o:p></o:p></span></p><div><div><div><div><p class=MsoNormal><span lang=EN-US>This fixes it by forcing the evaluation of the decode where it can be caught:<o:p></o:p></span></p></div><div><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div><div><p class=MsoNormal>return $ Right $! TE.decodeUtf8 bufferStrict<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>or <o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Right <$> evaluate (TE.decodeUtf8 bufferStrict)<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><span style='color:#1F497D'><snip></span><o:p></o:p></p></div></div></div></div></div><div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br /> <table style="border-top: 1px solid #D3D4DE;">
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