<div dir="ltr"><font color="#003333"><font size="2"><font face="verdana,sans-serif">Thanks. I tried the first two, which worked. <br><br>Previously I had tried:<br><br></font></font></font><div style="margin-left: 40px;"><font color="#003333"><font size="2"><font face="verdana,sans-serif">> let (zipWithPlus :: Num a => [a] -> [a] -> [a]) = zipWith (+)</font></font></font><br>
<br><font color="#003333"><font size="2"><font face="verdana,sans-serif"><span style="color: rgb(204, 0, 0);"><interactive>:1:5:</span></font></font></font><br style="color: rgb(204, 0, 0);"><font color="#003333"><font size="2"><font face="verdana,sans-serif"><span style="color: rgb(204, 0, 0);"> Illegal signature in pattern: (Num a) => [a] -> [a] -> [a]</span></font></font></font><br style="color: rgb(204, 0, 0);">
<font color="#003333"><font size="2"><font face="verdana,sans-serif"><span style="color: rgb(204, 0, 0);"> Use -XScopedTypeVariables to permit it</span></font></font></font><br></div><font color="#003333"><font size="2"><font face="verdana,sans-serif"><br>
I tried setting -XScopedTypeVariables. When I ran it again I got a different error message: <br><br></font></font></font><div style="margin-left: 40px;"><font color="#003333"><font size="2"><font face="verdana,sans-serif">Prelude> let (zipWithPlus :: Num a => [a] -> [a] -> [a]) = zipWith (+)</font></font></font><br>
<br><br><font style="color: rgb(204, 0, 0);" color="#003333"><font size="2"><font face="verdana,sans-serif"><interactive>:1:5:</font></font></font><br style="color: rgb(204, 0, 0);"><font style="color: rgb(204, 0, 0);" color="#003333"><font size="2"><font face="verdana,sans-serif"> Illegal polymorphic or qualified type:</font></font></font><br style="color: rgb(204, 0, 0);">
<font style="color: rgb(204, 0, 0);" color="#003333"><font size="2"><font face="verdana,sans-serif"> forall a. (Num a) => [a] -> [a] -> [a]</font></font></font><br style="color: rgb(204, 0, 0);"><font style="color: rgb(204, 0, 0);" color="#003333"><font size="2"><font face="verdana,sans-serif"> Perhaps you intended to use -XRankNTypes or -XRank2Types</font></font></font><br style="color: rgb(204, 0, 0);">
<font style="color: rgb(204, 0, 0);" color="#003333"><font size="2"><font face="verdana,sans-serif"> In a pattern type signature: (Num a) => [a] -> [a] -> [a]</font></font></font><br style="color: rgb(204, 0, 0);">
<font style="color: rgb(204, 0, 0);" color="#003333"><font size="2"><font face="verdana,sans-serif"> In the pattern: zipWithPlus :: (Num a) => [a] -> [a] -> [a]</font></font></font><br style="color: rgb(204, 0, 0);">
<font style="color: rgb(204, 0, 0);" color="#003333"><font size="2"><font face="verdana,sans-serif"> In a pattern binding:</font></font></font><br style="color: rgb(204, 0, 0);"><font style="color: rgb(204, 0, 0);" color="#003333"><font size="2"><font face="verdana,sans-serif"> (zipWithPlus :: (Num a) => [a] -> [a] -> [a]) = zipWith (+)</font></font></font><br>
</div><font color="#003333"><font size="2"><font face="verdana,sans-serif"><br><br clear="all"></font></font></font><div dir="ltr"><font style="color: rgb(0, 51, 51); font-family: verdana,sans-serif;" size="2"><br>-- Russ Abbott<br>
______________________________________<br> Professor, Computer Science<br> California State University, Los Angeles<br><br> Google voice: 424-242-USA0 (last character is zero)<br> blog: <a href="http://russabbott.blogspot.com/" target="_blank">http://russabbott.blogspot.com/</a><br>
vita: <a href="http://sites.google.com/site/russabbott/" target="_blank">http://sites.google.com/site/russabbott/</a><br>______________________________________<br></font></div><br>
<br><br><div class="gmail_quote">On Thu, Sep 30, 2010 at 12:48 PM, Daniel Fischer <span dir="ltr"><<a href="mailto:daniel.is.fischer@web.de">daniel.is.fischer@web.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
let zipWithPlus xs ys = zipWith (+) xs ys</blockquote></div><br></div>