I'm not sure what you're using at the end of the identifier "search'", but it needs to be the single quote that's on the same key as the double quotes. I suspect that's where it's blowing up.<br>
<br><div class="gmail_quote">On Thu, May 28, 2009 at 9:56 PM, michael rice <span dir="ltr"><<a href="mailto:nowgate@yahoo.com">nowgate@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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<span style="font-family: courier,monaco,monospace,sans-serif;">This code, from YAHT (Section 8.4.2, PDF pg. 119 of 192) seems to have a problem. Code below.<br><br>Michael<br><br>=================<br><br>[michael@localhost ~]$ ghci</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;">GHCi, version 6.10.1: <a href="http://www.haskell.org/ghc/" target="_blank">http://www.haskell.org/ghc/</a> :? for help</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;">Loading package ghc-prim ... linking ... done.</span><br style="font-family: courier,monaco,monospace,sans-serif;"><span style="font-family: courier,monaco,monospace,sans-serif;">Loading package integer ... linking ... done.</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;">Loading package base ... linking ... done.</span><br style="font-family: courier,monaco,monospace,sans-serif;"><span style="font-family: courier,monaco,monospace,sans-serif;">Prelude> :l graph</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;">[1 of 1] Compiling Main ( graph.hs, interpreted )</span><br style="font-family: courier,monaco,monospace,sans-serif;"><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;">graph.hs:6:24: lexical error at character '\8217'</span><br style="font-family: courier,monaco,monospace,sans-serif;"><span style="font-family: courier,monaco,monospace,sans-serif;">Failed, modules loaded: none.</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;"><br>==============<br><br>Prelude> data Graph v e = Graph [(Int,v)] [(Int,Int,e)]</span><br style="font-family: courier,monaco,monospace,sans-serif;"><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;">search :: Graph v e -> Int -> Int -> Maybe [Int]</span><br style="font-family: courier,monaco,monospace,sans-serif;"><span style="font-family: courier,monaco,monospace,sans-serif;">search g@(Graph vl el) src dst</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;"> | src == dst = Just [src]</span><br style="font-family: courier,monaco,monospace,sans-serif;"><span style="font-family: courier,monaco,monospace,sans-serif;"> | otherwise = search’ el</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;"> where search’ [] = Nothing</span><br style="font-family: courier,monaco,monospace,sans-serif;"><span style="font-family: courier,monaco,monospace,sans-serif;"> search’ ((u,v,_):es)</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;"> | src == u =</span><br style="font-family: courier,monaco,monospace,sans-serif;"><span style="font-family: courier,monaco,monospace,sans-serif;"> case search g v dst of</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;"> Just p -> Just (u:p)</span><br style="font-family: courier,monaco,monospace,sans-serif;"><span style="font-family: courier,monaco,monospace,sans-serif;"> Nothing -> search’ es</span><br style="font-family: courier,monaco,monospace,sans-serif;">
<span style="font-family: courier,monaco,monospace,sans-serif;"> | otherwise = search’ es</span><br style="font-family: courier,monaco,monospace,sans-serif;"><br style="font-family: courier,monaco,monospace,sans-serif;">
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<br></blockquote></div><br>