<div dir="ltr">Turned out that I didn't need fold at all, just a proper groupBy.<div><br></div><div>As for these lines</div><div><br></div><div><blockquote class="gmail_quote" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
<blockquote class="gmail_quote" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">module Main (</blockquote>
<blockquote class="gmail_quote" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"> main</blockquote>
<blockquote class="gmail_quote" style="margin-top:0px;margin-right:0px;margin-bottom:0px;margin-left:0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">) where</blockquote>
</blockquote><div><br></div></div><div>they were generated by Leksah. Do you suggest to remove them? And what about Leksah as an IDE: do you use it?</div><div><br></div><div><br></div><div>Giacomo</div></div><div class="gmail_extra">
<br><br><div class="gmail_quote">On Wed, May 15, 2013 at 9:35 AM, Giacomo Tesio <span dir="ltr"><<a href="mailto:giacomo@tesio.it" target="_blank">giacomo@tesio.it</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Thanks a lot!<div><br></div><div>Yesterday on freenode's #haskell channel Cane noted how my laziness problem reside in the foldl use in <span style="color:rgb(80,0,80);font-family:arial,sans-serif;font-size:14px">foldTradingSample</span>.</div>
<div>I have to turn it into a foldr (but I'm still unsure how...)</div><span class="HOEnZb"><font color="#888888"><div><br></div><div><br></div><div>Giacomo</div></font></span></div><div class="HOEnZb"><div class="h5">
<div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, May 15, 2013 at 12:46 AM, Henk-Jan van Tuyl <span dir="ltr"><<a href="mailto:hjgtuyl@chello.nl" target="_blank">hjgtuyl@chello.nl</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>On Tue, 14 May 2013 11:22:27 +0200, Giacomo Tesio <<a href="mailto:giacomo@tesio.it" target="_blank">giacomo@tesio.it</a>> wrote:<br>
<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Hi, I'm trying to improve a small haskell program of mine.<br>
</blockquote></div>
:<br>
<br>
Some remarks:<br>
<br>
0) Use hlint (available on Hackage) for improvement suggestions<br>
1) You don't have to write the module heading in Main.hs, it is not a library (why export main?)<br>
2) Change "print" to "putStrLn" if you want to display messages without quotes<br>
2) switchArgs is only partially defined, add something like:<br>
switchArgs [x] = putStrLn $ "Unknown tool: " ++ x<br>
3) Use shorter lines, for example change:<div><br>
importTrades outDir csvFile = transformFile csvFile (foldTradingSample.<u></u>getTickWriteTrades) (saveTradingSamples outDir)<br>
<br></div>
to:<div><br>
importTrades outDir csvFile =<br>
transformFile<br>
csvFile<br>
(foldTradingSample.<u></u>getTickWriteTrades)<br>
(saveTradingSamples outDir)<br></div>
4) It is considered good practice, to write the function<br>
composition operator between spaces (change f.g to f . g)<br>
<br>
I have analyze your software further to see how sufficient laziness can be reached.<br>
<br>
Regards,<br>
Henk-Jan van Tuyl<br>
<br>
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</blockquote></div><br></div>
</div></div></blockquote></div><br></div>