<br><font size=2 face="sans-serif">Hello,</font>
<br>
<br><tt><font size=2>> For example, the natural and naive way to write
Andrew's "mean" function<br>
> doesn't involve tuples at all: simply tail recurse with two accumulator<br>
> parameters, and compute the mean at the end. GHC's strictness
analyser<br>
> does the right thing with this, so there's no need for seq, $!, or
the<br>
> like. It's about 3 lines of code.<br>
> </font></tt>
<br><tt><font size=2>Is this the code you mean?</font></tt>
<br>
<br><tt><font size=2> meanNat = go 0 0 where</font></tt>
<br><tt><font size=2> go s n [] = s / n</font></tt>
<br><tt><font size=2> go s n (x:xs) = go (s+x)
(n+1) xs</font></tt>
<br><tt><font size=2><br>
If so, bang patterns are still required bang patterns in ghc-6.8.2 to run
in constant memory:</font></tt>
<br>
<br><tt><font size=2> meanNat = go 0 0 where</font></tt>
<br><tt><font size=2> go s n [] = s / n</font></tt>
<br><tt><font size=2> go !s !n (x:xs) = go (s+x)
(n+1) xs</font></tt>
<br>
<br><tt><font size=2>Is there some other way to write it so that ghc will
essentially insert the bangs for me?</font></tt>
<br>
<br><tt><font size=2>-Jeff</font></tt>
<br>
<br>
<br>
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