Hi guys,<div><br></div><div>I just started learning some Haskell. I want to implement a mean function to compute the mean of a list. The signature of the function is:</div><div><font class="Apple-style-span" face="&#39;courier new&#39;, monospace">mean :: (Num a, Fractional b) =&gt; [a] -&gt; b</font></div>
<div>But when I implement this simple function, the compiler keep whining at me on type errors. I know this is wrong:</div><div><font class="Apple-style-span" face="&#39;courier new&#39;, monospace">mean xs = sum xs / length xs</font></div>
<div>But how to get it right? Thanks.</div>