[Starting to write about typeclasses
John Goerzen <jgoerzen@complete.org>**20070603204434] {
hunk ./en/ch05-typeclasses.xml 6
+  <para>
+    Typeclasses are one of the most powerful features in Haskell.  They
+    are also at the heart of some basic language features such as equality
+    testing and numeric operators.  Before we talk about what exactly
+    typeclasses are, though, we'd like to first explain the need for them.
+  </para>
+
+  <sect1 id="hs.typeclasses.need">
+    <title>The need for typeclasses</title>
+    <para>
+      Let's imaging that for some unfathomable reason, the designers of the
+      Haskell language neglected to implement the equality test
+      <function>==</function>.  Once you got over your shock at hearing this, 
+      you resolved to implement your own equality tests.  Your program
+      consisted of a simple <type>Color</type> type, and so your first
+      equality test is for this type.  Your first attempt might look like
+      this:
+    </para>
+  </sect1>
+
+
hunk ./en/ch05-typeclasses.xml 69
+
+  <sect1 id="hs.typeclasses.overlapping">
+    <title>Overlapping Instances</title>
+    <para>
+      FIXME
+    </para>
+  </sect1>
+
+  <sect1 id="hs.typeclasses.undecidable">
+    <title>Undecidable Instances</title>
+    <para>
+      FIXME
+    </para>
+  </sect1>
+
}