System.Event.Manager [1] contains the following type alias and Show instance:<br><br><pre><span class="hs-comment">-- | Callback invoked on I/O events.</span><br><a name="line-94"></a><a name="IOCallback"></a><span class="hs-keyword">type</span> <span class="hs-conid">IOCallback</span> <span class="hs-keyglyph">=</span> <span class="hs-conid">FdKey</span> <span class="hs-keyglyph">-&gt;</span> <span class="hs-conid">Event</span> <span class="hs-keyglyph">-&gt;</span> <span class="hs-conid">IO</span> <span class="hs-conid">()</span><br>

<a name="line-95"></a><br><a name="line-96"></a><span class="hs-keyword">instance</span> <span class="hs-conid">Show</span> <span class="hs-conid">IOCallback</span> <span class="hs-keyword">where</span><br><a name="line-97"></a>    <span class="hs-varid">show</span> <span class="hs-keyword">_</span> <span class="hs-keyglyph">=</span> <span class="hs-str">&quot;IOCallback&quot;</span></pre>

<br>This specialized instance conflicts with the more general instance Show (a -&gt; b) defined in Text.Show.Functions.<br><br>Stefan found this conflict when trying to compile the checkers package on ghc 7.0.3. I suspect it will arise with other packages as well.<br>

<br>My suggestion is to remove the specialized Show instance and instead import Text.Show.Functions as needed.<br><br>Other thoughts?<br><br>[1] <a href="http://hackage.haskell.org/packages/archive/base/4.3.1.0/doc/html/src/System-Event-Manager.html">http://hackage.haskell.org/packages/archive/base/4.3.1.0/doc/html/src/System-Event-Manager.html</a><br>

<br>  - Conal<br>